app/test: fix array overflow warning with gcc 4.5

app/test: fix array overflow warning with gcc 4.5

DPDK/app/test/test_cryptodev.c:
	In function 'test_snow3g_encrypted_authentication.clone.3':
DPDK/x86_64-ivshmem-linuxapp-gcc/include/rte_memcpy.h:796:14: error:
	array subscript is above array bounds

In lines like:
    rte_memcpy(sym_op->cipher.iv.data, iv, iv_len);
when "iv" is 64 bytes long array, and "iv_len" is "unsigned int",
compiler tries to evaluate also a code for array size larger than 255 bytes
long and reports error "array subscript is above array bounds" in line:
	rte_memcpy.h:796
    rte_mov128((uint8_t *)dst + 128, (const uint8_t *)src + 128);
caused by evaluation to:
    rte_mov128((uint8_t *)sym_op->cipher.iv.data + 128, (const uint8_t *)iv
			+ 128);
where "iv" is 64 bytes long buffer and "iv + 128" point out of it, gcc 4.5.

Using uint8_t as a size of copied block prevents to evaluate in rte_memcpy
code for length bigger than 255, causing the problem.

Fixes: 8bdf665fe6c0 ("app/test: add SNOW 3G")

Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>