Convert CONFIG_BOOTP_MAY_FAIL et al to Kconfig

This converts the following to Kconfig:
   CONFIG_BOOTP_MAY_FAIL
   CONFIG_BOOTP_VENDOREX
   CONFIG_BOOTP_BOOTFILESIZE
   CONFIG_BOOTP_NISDOMAIN
   CONFIG_BOOTP_TIMEOFFSET

Cc: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/integratorap_cm926ejs_defconfig b/configs/integratorap_cm926ejs_defconfig
index 2160887..52973da 100644
--- a/configs/integratorap_cm926ejs_defconfig
+++ b/configs/integratorap_cm926ejs_defconfig
@@ -20,6 +20,7 @@
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_ARMFLASH=y
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_BOOTP_BOOTFILESIZE=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y