Porting guide: Improve bl1_plat_mem_check() doc
Porting guide: Improve bl1_plat_mem_check() doc

This patch fixes the type of the return value of bl1_plat_mem_check()
in the porting guide. It also specifies the expected return value.

Change-Id: I7c437342b8bfb1e621d74b2edf0aaf97b913216a
Signed-off-by: Sandrine Bailleux <4b69fcfca8da45b0c11ecda5434c5da526575d9d@arm.com>

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