efi/gop: Move variable declarations into loop block

Declare the variables inside the block where they're used.

Get rid of a couple of redundant initializers.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200320020028.1936003-7-nivedita@alum.mit.edu


Signed-off-by: Ard Biesheuvel <ardb@kernel.org>