soc/intel/skylake: Remove unwanted spi_release call

Skylake uses a special SPI Flash controller and does not require
spi_claim_bus and spi_release_bus functionality. This was a leftover
call from earlier cleanup, so remove it.

Change-Id: Iea260813cf72b94b7e7c661dbe494a74351dc357
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17729
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/skylake/flash_controller.c

@@ -191,7 +191,6 @@ int pch_hwseq_erase(const struct spi_flash *flash, u32 offset, size_t len)
 		len, start);
 
 out:
-	spi_release_bus(&flash->spi);
 	return ret;
 }