ANDROID: trusty: use in-kernel integer types

Linux kernel code conventionally uses u8, u16, u32, etc. instead of the
stdint-style uint8_t, uint16_t, uint32_t, etc.  So replace the
stdint-style types with the Linux-style types.

Don't make this change in arm_ffa.h or trusty-log.h, since there is a
copy of these headers in non-Linux code, and there is a desire to keep
the copies the same.

Change-Id: I0a0239cbda9a32b004581e80e5d4420cee7ee429
Signed-off-by: Eric Biggers <ebiggers@google.com>