efi/esrt: Clean up efi_esrt_init

Remove an unused variable in __init efi_esrt_init().
Simplify a logical constraint.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Link: https://lore.kernel.org/r/20200223204557.114634-1-xypron.glpk@gmx.de


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