ANDROID: GKI: enable CONFIG_SPI_SLAVE=y

The SPI[1] is a synchronous four wire serial link used to connect
microcontrollers to sensors, memory, and peripherals.
SPI_SLAVE[2] supports SPI slave controller to the Linux SPI subsystem.
In order to support the feature from GKI kernel, we need to enable SPI_SLAVE.

[1]: https://www.kernel.org/doc/html/latest/spi/spi-summary.html
[2]: https://lwn.net/Articles/723440/



Bug: 316768184
Signed-off-by: Bumyong Lee <bumyong.lee@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1802e7e67b9cf12b2b4eaec638728f1e56382ee0