arm64: Define readq and writeq for driver module using

when compiling with allmodconfig, CONFIG_64BIT=y the file
drivers/base/regmap/regmap-mmio.c will use readq and writeq so we need
implement these functions.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>