Convert CONFIG_LBA48 et al to Kconfig

This converts the following to Kconfig:
   CONFIG_LBA48
   CONFIG_SYS_64BIT_LBA

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/slimbootloader_defconfig b/configs/slimbootloader_defconfig
index 2e938b6..b6b9f88 100644
--- a/configs/slimbootloader_defconfig
+++ b/configs/slimbootloader_defconfig
@@ -28,6 +28,8 @@
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
 # CONFIG_ACPIGEN is not set
+CONFIG_LBA48=y
+CONFIG_SYS_64BIT_LBA=y
 # CONFIG_PCI_PNP is not set
 CONFIG_CONSOLE_SCROLL_LINES=5
 # CONFIG_GZIP is not set