efi: Delete deprecated parameter comments

Delete deprecated parameter comments to  fix warnings reported by make
W=1.
drivers/firmware/efi/vars.c:428: warning: Excess function parameter
'atomic' description in 'efivar_init'

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Link: https://lore.kernel.org/r/1600914018-12697-1-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>