Replace equivalent (and partially incorrect) scatter-gather functions
with ones from crypto-API.

The replacement is motivated by page-faults in sg_copy_part triggered
by successive calls to crypto_hash_update. The following fault appears
after calling crypto_ahash_update twice, first with 13 and then
with 285 bytes:

Unable to handle kernel paging request for data at address 0x00000008
Faulting instruction address: 0xf9bf9a8c
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=8 CoreNet Generic
Modules linked in: tcrypt(+) caamhash caam_jr caam tls
CPU: 6 PID: 1497 Comm: cryptomgr_test Not tainted
3.12.19-rt30-QorIQ-SDK-V1.6+g9fda9f2 #75
task: e9308530 ti: e700e000 task.ti: e700e000
NIP: f9bf9a8c LR: f9bfcf28 CTR: c0019ea0
REGS: e700fb80 TRAP: 0300   Not tainted
(3.12.19-rt30-QorIQ-SDK-V1.6+g9fda9f2)
MSR: 00029002 <CE,EE,ME>  CR: 44f92024  XER: 20000000
DEAR: 00000008, ESR: 00000000

GPR00: f9bfcf28 e700fc30 e9308530 e70b1e55 00000000 ffffffdd e70b1e54 0bebf888
GPR08: 902c7ef5 c0e771e2 00000002 00000888 c0019ea0 00000000 00000000 c07a4154
GPR16: c08d0000 e91a8f9c 00000001 e98fb400 00000100 e9c83028 e70b1e08 e70b1d48
GPR24: e992ce10 e70b1dc8 f9bfe4f4 e70b1e55 ffffffdd e70b1ce0 00000000 00000000
NIP [f9bf9a8c] sg_copy+0x1c/0x100 [caamhash]
LR [f9bfcf28] ahash_update_no_ctx+0x628/0x660 [caamhash]
Call Trace:
[e700fc30] [f9bf9c50] sg_copy_part+0xe0/0x160 [caamhash] (unreliable)
[e700fc50] [f9bfcf28] ahash_update_no_ctx+0x628/0x660 [caamhash]
[e700fcb0] [f954e19c] crypto_tls_genicv+0x13c/0x300 [tls]
[e700fd10] [f954e65c] crypto_tls_encrypt+0x5c/0x260 [tls]
[e700fd40] [c02250ec] __test_aead.constprop.9+0x2bc/0xb70
[e700fe40] [c02259f0] alg_test_aead+0x50/0xc0
[e700fe60] [c02241e4] alg_test+0x114/0x2e0
[e700fee0] [c022276c] cryptomgr_test+0x4c/0x60
[e700fef0] [c004f658] kthread+0x98/0xa0
[e700ff40] [c000fd04] ret_from_kernel_thread+0x5c/0x64
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>