Remove "select MSCC_BITBANG_SPI_GPIO" since Kbuild option was deleted
back in commit ace9c103df:
commit ace9c103df
Author: Lars Povlsen <lars.povlsen@microchip.com>
Date: Tue Jan 8 10:38:35 2019 +0100
mips: gpio: mscc: Obsoleted gpio-mscc-bitbang-spi.c