cmd: ums: abort mounting by pressing any key

This patch introduses config which allows interrupt run of usb
mass storage with any key. This is especially useful on devices
with limited input capabilities like tablets and smatphones which
have only gpio keys in direct access.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 8138ab9..8c9b430 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1552,6 +1552,12 @@
 	  export a block device: U-Boot, the USB device, acts as a simple
 	  external hard drive plugged on the host USB port.
 
+config CMD_UMS_ABORT_KEYED
+	bool "UMS abort with any key"
+	depends on CMD_USB_MASS_STORAGE
+	help
+	  Allow interruption of usb mass storage run with any key pressed.
+
 config CMD_PVBLOCK
 	bool "Xen para-virtualized block device"
 	depends on XEN