It should already work like below.
int8x16_t vector;
vector=vld1q_s8((int8_t *) srcimg.data);
int8x16_t
is a vector type, created to make it easy to read vector layout.
int8_t
is what you would call a byte.
Reading it aloud should sound like "load into a quad register from this byte stream".
If you also check gcc arm intrinsics page, you shouldn't be able to find any pointer to those vector types. They mean to map to SIMD
registers, and you don't generally talk pointers to registers.
If you would like to get more information about neon programming you can check ARM's website and this blog series.