kernel: merge kmod-fbcon with kmod-fb

kernel: merge kmod-fbcon with kmod-fb

As of commit in kernel:
6104c37094 fbcon: Make fbcon a built-time depency for fbdev
framebuffer console is build in into framebuffer module and there's no
standalone fbcon module. Therefore drop the kmod-fbcon and enable
console in kmod-fb. The only targets which use these modules are imx6
and geode, both are on kernel 4.14 so no fallback for other kernels is
introduced.
Being at that this commit also fixes autoload of fbdev for x86.

Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>
(backported from 9c0ddafd4663948fe5c6f3f4a7a7601fdbb36737)