rockchip: Include stdint header in plat_sip_calls.c
rockchip: Include stdint header in plat_sip_calls.c

This includes the stdint header to declare the various types used within
the file, preventing build errors with recent GCC versions.

Change-Id: I9e7e92bb31deb58d4ff2732067dd88b53124bcc9
Signed-off-by: Paul Kocialkowski <1a73af9e7ae00182733b2292511b814be66f065f@paulk.fr>

lsigithub/arm-trusted-firmware_public,lsigithub/arm-trusted-firmware_public,achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware