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/minnowmax_defconfig b/configs/minnowmax_defconfig
index 446c2f2..0b317bc 100644
--- a/configs/minnowmax_defconfig
+++ b/configs/minnowmax_defconfig
@@ -19,6 +19,7 @@
 CONFIG_FIT_SIGNATURE=y
 CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y
+CONFIG_SHOW_BOOT_PROGRESS=y
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="root=/dev/sdb3 init=/sbin/init rootwait ro"
 CONFIG_SYS_CONSOLE_INFO_QUIET=y