Fixed uninitialized memory reported by Valgrind

Valgrind reports some issues due to uninitialized
values. For instance:

Use of uninitialised value of size 8
   at 0xEA2AC1: emulate_AESDEC (in LibTestApp/ipsec_MB_testapp)
   by 0x476D12: ??? (sse/aes192_cbc_dec_by4_sse.asm:387)
   by 0x1FFEFF075F: ???
   by 0x5496E1F: ???
   by 0x1FFEFF4A0F: ???
   by 0x1FFEFF4BBF: ???
   by 0x5492C7F: ???
   by 0x1FFEFF49FF: ???
   by 0x1FFEFF4A1F: ???
   by 0x3F: ???
   by 0x1FFEFF4A5F: ???
   by 0x7: ???
 Uninitialised value was created by a stack allocation
   at 0x403B37: customop_test (customop_test.c:198)

Therefore, some memory has been set to 0 after initialization.

Change-Id: Ie2dfe36b68ca59f9410c4b2d40647aaba429a5ee