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/efi-x86_app_defconfig b/configs/efi-x86_app_defconfig
index ea3743d..e732ec0 100644
--- a/configs/efi-x86_app_defconfig
+++ b/configs/efi-x86_app_defconfig
@@ -6,6 +6,7 @@
 CONFIG_TARGET_EFI_APP=y
 CONFIG_DEBUG_UART=y
 CONFIG_FIT=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