efi: EFI_EARLYCON should depend on EFI

efi: EFI_EARLYCON should depend on EFI

CONFIG_EFI_EARLYCON defaults to yes, and thus is enabled on systems that
do not support EFI, or do not have EFI support enabled, but do satisfy
the symbol's other dependencies.

While drivers/firmware/efi/ won't be entered during the build phase if
CONFIG_EFI=n, and drivers/firmware/efi/earlycon.c itself thus won't be
built, enabling EFI_EARLYCON does force-enable CONFIG_FONT_SUPPORT and
CONFIG_ARCH_USE_MEMREMAP_PROT, and CONFIG_FONT_8x16, which is
undesirable.

Fix this by making CONFIG_EFI_EARLYCON depend on CONFIG_EFI.

This reduces kernel size on headless systems by more than 4 KiB.

Fixes: 69c1f396f25b805a ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20201124191646.3559757-1-geert@linux-m68k.org
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>