Booting the Linux kernel on Nokia RM-680 board has been broken since
2.6.39 due to the following:

[    0.217193] omap_hwmod: timer12: enabling
[    0.221435] Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa304010
[    0.229431] Internal error: : 1028 [#1] SMP
[    0.233825] Modules linked in:
[    0.237060] CPU: 0    Not tainted  (3.2.0-rc4-dirty #46)
[    0.242645] PC is at _update_sysc_cache+0x2c/0x7c
[    0.247589] LR is at _enable+0x1b0/0x2d8
[    0.251708] pc : [<c0026108>]    lr : [<c0026df4>]    psr: 40000013
[    0.251708] sp : ef831f40  ip : ef82f380  fp : c06ac0c0
[    0.263702] r10: 00000000  r9 : c05dfb2c  r8 : ef830000
[    0.269165] r7 : c0027494  r6 : 00000000  r5 : 00000000  r4 : c06608b0
[    0.276000] r3 : fa304000  r2 : 00000010  r1 : c0661e28  r0 : c06608b0
[    0.282806] Flags: nZcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[    0.290405] Control: 10c5387d  Table: 80004019  DAC: 00000017
[    0.296417] Process swapper (pid: 1, stack limit = 0xef8302f8)
[    0.302520] Stack: (0xef831f40 to 0xef832000)
[    0.307098] 1f40: c06608b0 c0026df4 c06ad094 c0035120 00000001 c06608b0 00000000 c0027530
[    0.315612] 1f60: c0027604 ef830000 c05dfb2c c06608b0 c0642ac0 c0025bf0 c0621234 c062120c
[    0.324127] 1f80: c0621738 00000013 ef830000 c05dfb6c c0621234 c0008688 c062c880 c009eadc
[    0.332641] 1fa0: 0000005f 00000000 c0621738 35390013 00000000 00000000 00000000 0000019a
[    0.341156] 1fc0: c0681cf4 c0621234 c062120c c0621738 00000013 00000000 00000000 00000000
[    0.349670] 1fe0: 00000000 c05d5298 00000000 c05d5200 c0014fa8 c0014fa8 ffff0000 ffff0000
[    0.358184] [<c0026108>] (_update_sysc_cache+0x2c/0x7c) from [<c0026df4>] (_enable+0x1b0/0x2d8)
[    0.367248] [<c0026df4>] (_enable+0x1b0/0x2d8) from [<c0027530>] (_setup+0x9c/0x170)
[    0.375335] [<c0027530>] (_setup+0x9c/0x170) from [<c0025bf0>] (omap_hwmod_for_each+0x38/0x58)
[    0.384307] [<c0025bf0>] (omap_hwmod_for_each+0x38/0x58) from [<c05dfb6c>] (omap_hwmod_setup_all+0x40/0xa0)
[    0.394409] [<c05dfb6c>] (omap_hwmod_setup_all+0x40/0xa0) from [<c0008688>] (do_one_initcall+0x34/0x180)
[    0.404296] [<c0008688>] (do_one_initcall+0x34/0x180) from [<c05d5298>] (kernel_init+0x98/0x144)
[    0.413452] [<c05d5298>] (kernel_init+0x98/0x144) from [<c0014fa8>] (kernel_thread_exit+0x0/0x8)
[    0.422576] Code: e3130c01 1590304c 0590304c 119320b2 (07932002)
[    0.429046] ---[ end trace 1b75b31a2719ed1c ]---
[    0.433959] Kernel panic - not syncing: Attempted to kill init!

Timer 12 is not necessarily available on non-GP devices (see e.g.
http://marc.info/?l=linux-omap&m=129433066521102&w=2), so it should be
registered only on GP OMAPs. With this change it's again possible to
boot RM-680 into the shell. Tested with 3.2-rc4.
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
[paul@pwsan.com: changed subject line]
Signed-off-by: Paul Walmsley <paul@pwsan.com>