efi/earlycon: Fix early printk for wider fonts

efi/earlycon: Fix early printk for wider fonts

[ Upstream commit 8f592ada59b321d248391bae175cd78a12972223 ]

When I play with terminus fonts I noticed the efi early printk does
not work because the earlycon code assumes font width is 8.

Here add the code to adapt with larger fonts.  Tested with all kinds
of kernel built-in fonts on my laptop. Also tested with a local draft
patch for 14x28 !bold terminus font.

Signed-off-by: Dave Young <dyoung@redhat.com>
Link: https://lore.kernel.org/r/20200412024927.GA6884@dhcp-128-65.nay.redhat.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>