x86/efi: Remove references to no-longer-used efi_have_uv1_memmap()

In removing UV1 support, efi_have_uv1_memmap is no longer used.

Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lkml.kernel.org/r/20200713212955.786177105@hpe.com