am33xx: Finish migration of CONFIG_AM33XX/AM43XX

Almost all users of CONFIG_AM33XX/AM43XX have been migrated.  Finish
moving the last few over to Kconfig, and put all of the boards under the
appropriate Kconfig chocie now.  This board choice is non-optional, so
remove that keyword on am33xx.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/brppt1_spi_defconfig b/configs/brppt1_spi_defconfig
index 333e204..27a4124 100644
--- a/configs/brppt1_spi_defconfig
+++ b/configs/brppt1_spi_defconfig
@@ -3,6 +3,7 @@
 CONFIG_SPL_GPIO_SUPPORT=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
+CONFIG_AM33XX=y
 CONFIG_TARGET_BRPPT1=y
 CONFIG_SPL_MMC_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y