arch/neon.c: check result of fread()

Fix for:

CID 1128384 (#1 of 1): Ignoring number of bytes read (CHECKED_RETURN)
 check_return: fread(void * restrict, size_t, size_t, FILE * restrict)
 returns the number of bytes read, but it is ignored.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>