Convert CONFIG_AT91_GPIO_PULLUP to Kconfig

This converts the following to Kconfig:
   CONFIG_AT91_GPIO_PULLUP

Cc: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/axm_defconfig b/configs/axm_defconfig
index e27f0b7..b6b4104 100644
--- a/configs/axm_defconfig
+++ b/configs/axm_defconfig
@@ -12,6 +12,7 @@
 CONFIG_SYS_MALLOC_LEN=0x460000
 CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_TARGET_TAURUS=y
+CONFIG_AT91_GPIO_PULLUP=y
 CONFIG_SPL_GPIO=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y