drivers/rtc/rtc-snvs: fix suspend/resume

The alarm interrupt handler also reads registers which are part of SNVS
and need clocks enabled.  However, the resume function is called after
IRQ's have been enabled, hence this leads to a abort:

    Unhandled fault: external abort on non-linefetch (0x1008) at 0x908c604c
    Internal error: : 1008 [#1] ARM
    Modules linked in:
    CPU: 0 PID: 421 Comm: sh Not tainted 3.18.0-rc5-00135-g0689c67-dirty #1592
    task: 8e03e800 ti: 8cad8000 task.ti: 8cad8000
    PC is at snvs_rtc_irq_handler+0x14/0x74
    LR is at handle_irq_event_percpu+0x3c/0x144

Fix this by using the .{suspend/resume}_noirq callbacks instead of
.{suspend/resume} .

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>