drivers: acpi: add dependency of EFI for arm64

As Ard suggested, CONFIG_ACPI && !CONFIG_EFI doesn't make sense on arm64,
while CONFIG_ACPI and CONFIG_CPU_BIG_ENDIAN doesn't make sense either.

As CONFIG_EFI already has a dependency of !CONFIG_CPU_BIG_ENDIAN, it is
good enough to add a dependency of CONFIG_EFI to avoid any useless
combination of configuration.

This bug, reported by Will, will be revealed when my patch series,
"arm64: kexec,kdump: fix boot failures on acpi-only system," is applied
and the kernel is built under allmodconfig.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>