imxtract: specify max gunzip size

Specify max gunzip size from config to override SYS_XIMG_LEN
default value wich is 0x800000. In case we have a large portion of FIT
image, for example gzipped kernel with decompressed size large than
0x800000 we should enlarge imxract area, otherwise extracting it will
fail.

It used to be a hardcoded define in cmd/ximg.c and we are moving it to
config.

Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 24bfbe5..5a7678f 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -495,6 +495,16 @@
 	help
 	  Extract a part of a multi-image.
 
+config SYS_XIMG_LEN
+	hex "imxtract max gunzip size"
+	default 0x800000
+	depends on CMD_XIMG && GZIP
+	help
+	  This provides the size of the commad-line argument area
+	  used by imxtract for extracting pieces of FIT image.
+	  It should be large enough to fit uncompressed size of
+	  FIT piece we are extracting.
+
 config CMD_SPL
 	bool "spl export - Export boot information for Falcon boot"
 	depends on SPL