spl: fit: Eanble GZIP support for image decompression

Add Kconfig option SPL_GZIP and SPL_ZLIB to enable gunzip support for
SPL boot, eg. falcon boot compressed kernel image.

Signed-off-by: York Sun <york.sun@nxp.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/Kconfig b/lib/Kconfig
index fe337ac..628ef8d 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -176,6 +176,18 @@
 	bool "Enable LZO decompression support"
 	help
 	  This enables support for LZO compression algorithm.r
+
+config SPL_GZIP
+	bool "Enable gzip decompression support for SPL build"
+	select SPL_ZLIB
+	help
+	  This enables support for GZIP compression altorithm for SPL boot.
+
+config SPL_ZLIB
+	bool
+	help
+	  This enables compression lib for SPL boot.
+
 endmenu
 
 config ERRNO_STR