chore(docs): fix broken url references to arm procedure call

Couple for urls under section: `5.6. Use of built-in C and libc
data types` from docs has broken urls since the new arm procedure
call doc is moved to be part of `ARM-software/abi-aa`.

Change-Id: Ied184ed56c8335d4cbc687e56962439091a18e42
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>