During noirq suspend phase the Raspberry Pi power driver suffer of
firmware property timeouts. The reason is that the IRQ of the underlying
BCM2835 mailbox is disabled and rpi_firmware_property_list() will always
run into a timeout [1].

Since the VideoCore side isn't consider as a wakeup source, set the
IRQF_NO_SUSPEND flag for the mailbox IRQ in order to keep it enabled
during suspend-resume cycle.

[1]
PM: late suspend of devices complete after 1.754 msecs
WARNING: CPU: 0 PID: 438 at drivers/firmware/raspberrypi.c:128
 rpi_firmware_property_list+0x204/0x22c
Firmware transaction 0x00028001 timeout
Modules linked in:
CPU: 0 PID: 438 Comm: bash Tainted: G         C         6.9.3-dirty #17
Hardware name: BCM2835
Call trace:
unwind_backtrace from show_stack+0x18/0x1c
show_stack from dump_stack_lvl+0x34/0x44
dump_stack_lvl from __warn+0x88/0xec
__warn from warn_slowpath_fmt+0x7c/0xb0
warn_slowpath_fmt from rpi_firmware_property_list+0x204/0x22c
rpi_firmware_property_list from rpi_firmware_property+0x68/0x8c
rpi_firmware_property from rpi_firmware_set_power+0x54/0xc0
rpi_firmware_set_power from _genpd_power_off+0xe4/0x148
_genpd_power_off from genpd_sync_power_off+0x7c/0x11c
genpd_sync_power_off from genpd_finish_suspend+0xcc/0xe0
genpd_finish_suspend from dpm_run_callback+0x78/0xd0
dpm_run_callback from device_suspend_noirq+0xc0/0x238
device_suspend_noirq from dpm_suspend_noirq+0xb0/0x168
dpm_suspend_noirq from suspend_devices_and_enter+0x1b8/0x5ac
suspend_devices_and_enter from pm_suspend+0x254/0x2e4
pm_suspend from state_store+0xa8/0xd4
state_store from kernfs_fop_write_iter+0x154/0x1a0
kernfs_fop_write_iter from vfs_write+0x12c/0x184
vfs_write from ksys_write+0x78/0xc0
ksys_write from ret_fast_syscall+0x0/0x54
Exception stack(0xcc93dfa8 to 0xcc93dff0)
[...]
PM: noirq suspend of devices complete after 3095.584 msecs

Link: https://github.com/raspberrypi/firmware/issues/1894
Fixes: 0bae6af6 ("mailbox: Enable BCM2835 mailbox support")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>