boot: android: fix extra command line support

Check that the value at the address kcmdline_extra is not 0
instead of checking the address value itself keeping it
consistent with what is done for kcmdline.

Fixes: b36b227b ("android: boot: support extra command line")
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Nicolas Belin <nbelin@baylibre.com>
Link: https://lore.kernel.org/r/20241217-fix-bootargs-concatenation-v2-1-b2fd7cf4e130@baylibre.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
diff --git a/boot/image-android.c b/boot/image-android.c
index cd01278..5715828 100644
--- a/boot/image-android.c
+++ b/boot/image-android.c
@@ -292,7 +292,7 @@
 		len += strlen(img_data.kcmdline);
 	}
 
-	if (img_data.kcmdline_extra) {
+	if (*img_data.kcmdline_extra) {
 		printf("Kernel extra command line: %s\n", img_data.kcmdline_extra);
 		len += strlen(img_data.kcmdline_extra);
 	}
@@ -316,7 +316,7 @@
 	if (*img_data.kcmdline)
 		strcat(newbootargs, img_data.kcmdline);
 
-	if (img_data.kcmdline_extra) {
+	if (*img_data.kcmdline_extra) {
 		strcat(newbootargs, " ");
 		strcat(newbootargs, img_data.kcmdline_extra);
 	}