Convert CONFIG_SHOW_BOOT_PROGRESS to Kconfig

This converts the following to Kconfig:
   CONFIG_SHOW_BOOT_PROGRESS

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/lsxhl_defconfig b/configs/lsxhl_defconfig
index daeecb5..9d12ef9 100644
--- a/configs/lsxhl_defconfig
+++ b/configs/lsxhl_defconfig
@@ -8,6 +8,7 @@
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_SYS_EXTRA_OPTIONS="LSXHL"
 CONFIG_API=y
+CONFIG_SHOW_BOOT_PROGRESS=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/sda2"