mb/google/hatch: Select BOARD_ROMSIZE_KB_16384 by default

All hatch and puff variants use 16MiB SPI flash except the legacy ones
which used 32MiB flash. Kconfig.name is updated to select
BOARD_ROMSIZE_KB_32768 only for the legacy variants and
BOARD_GOOGLE_HATCH_COMMON selects BOARD_ROMSIZE_KB_16384 by default if
BOARD_ROMSIZE_KB_32768 is not selected.

TEST=Verified using abuild --timeless that all hatch variants generate
the same coreboot.rom image with and without this change.

Change-Id: I708506182966936ea38562db8b0325470e34c908
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41662
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: V Sowmya <v.sowmya@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/hatch/Kconfig

@@ -15,6 +15,7 @@ config BOARD_GOOGLE_BASEBOARD_PUFF
 
 config BOARD_GOOGLE_HATCH_COMMON
 	def_bool n
+	select BOARD_ROMSIZE_KB_16384 if !BOARD_ROMSIZE_KB_32768
 	select DRIVERS_GENERIC_GPIO_KEYS
 	select DRIVERS_GENERIC_MAX98357A
 	select DRIVERS_I2C_DA7219