x86/fault: Bypass no_context() for implicit kernel faults from usermode

Drop an indentation level and remove the last user_mode(regs) == true
caller of no_context() by directly OOPSing for implicit kernel faults
from usermode.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/6e3d1129494a8de1e59d28012286e3a292a2296e.1612924255.git.luto@kernel.org