Convert CONFIG_USE_BOOTCOMMAND et al to Kconfig

This converts the following to Kconfig:
   CONFIG_USE_BOOTCOMMAND
   CONFIG_BOOTCOMMAND
   CONFIG_RAMBOOTCOMMAND
   CONFIG_NFSBOOTCOMMAND

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/eb_cpu5282_internal_defconfig b/configs/eb_cpu5282_internal_defconfig
index ad0f6f8..0c00ead 100644
--- a/configs/eb_cpu5282_internal_defconfig
+++ b/configs/eb_cpu5282_internal_defconfig
@@ -7,6 +7,8 @@
 CONFIG_SYS_LOAD_ADDR=0x20000
 CONFIG_SYS_EXTRA_OPTIONS="SYS_MONITOR_BASE=0xF0000418"
 CONFIG_BOOTDELAY=5
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="printenv"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_MISC_INIT_R=y
 # CONFIG_AUTO_COMPLETE is not set