ARM: qemu-arm: enable RTC

QEMU provides an emulated ARM AMBA PrimeCell PL031 RTC.

The patch sets the base address in the board include file according to the
definition in hw/arm/virt.c of the QEMU source. It defines the Kconfig
option for the existing driver, and enables the RTC driver in
qemu_arm64_defconfig and qemu_arm_defconfig as well as the date command.

We need an RTC to provide the GetTime() runtime service in the UEFI
subsystem.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Tested-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>