4BA: Add spi_exit_4ba function to switch SPI flash to 3-byte addressing

Change-Id: I553e7fb5028f35e14a3a81b3fa8903c1b321a223
Signed-off-by: Ed Swierk <eswierk@skyportsystems.com>
Reviewed-on: https://review.coreboot.org/20509
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
3 files changed