soc: qcom: pil-msa: Add check for valid firmware data

When fw->data = NULL it will lead to

Unable to handle kernel NULL pointer dereference at virtual address
00000000  pgd = e4f74000
[00000000] *pgd=a4f7e831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 1 Comm: init Not tainted 3.10.28-119835-eng #1
PC is at memcpy+0x48/0x330 LR is at pil_mss_reset_load_mba+0x22c/0x3d8
pc : [<c034cbe8>]    lr : [<c04186e4>]    psr: 200d0013
sp : e7469dac  ip : 00000000 fp : 00000001
r10: 00100000  r9 : c1170ea8 r8 : c04188a4
r7 : eee00000  r6 : e5b428b8 r5 : e5b42810  r4 : e4c1559c
r3 : aee00000  r2 : 0003f240 r1 : 00000000  r0 : eee00000

Do not proceed with modem reset in case of mba data is NULL.

Change-Id: I939c7fdac33cdee3dd7451b3cafd74529706f5e1
Signed-off-by: Taniya Das <tdas@codeaurora.org>