ArmPlatformPkg: Enable support for flash in 64-bit address space

ArmPlatformPkg: Enable support for flash in 64-bit address space

The existing NOR Flash DXE and StandaloneMm driver supports NOR flash
devices connected in the 32-bit address space. Extend these drivers to
allow NOR flash devices connected to 64-bit address space to be usable
as well. Also, convert the base address and size sanity check from
ASSERT() to if condition so that even if the firmware is build in
release mode, it can return error if the parameter(s) is/are invalid.

Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Tested-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>