Remove Kconfig variable that has no effect

MAINBOARD_HAS_BOOTBLOCK_INIT is only declared once and selected elsewhere
(with no overlap), and never read. Remove it.

Change-Id: Ica1f16182b556dbf4a3b747237af74bcc4c0608c
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/10254
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/mainboard/google/nyan/Kconfig

@@ -27,7 +27,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	select EC_GOOGLE_CHROMEEC_SPI
 	select EC_SOFTWARE_SYNC
 	select TEGRA124_MODEL_CD570M
-	select MAINBOARD_HAS_BOOTBLOCK_INIT
 	select MAINBOARD_DO_NATIVE_VGA_INIT
 	select BOARD_ROMSIZE_KB_4096
 	select SPI_FLASH