The temp val should be uint64_t in read_sysreg64 instead of uint32_t.
The incorrect type uint32_t will cause an issue:
mrrc instruction needs 2 registers when reading from a 64-bit system
register. The type uint32_t tells GCC only to save/restore one register,
so after the mrrc is executed, the other would clash.
Signed-off-by: Jaxson Han <jaxson.han@arm.com>