cmd: abootimg: Prevent use of unintialised variable

Initialise vhdr to prevent its use when uninitialised.

This issue was found with Smatch.

Fixes: 636da2039aea (android: boot: support boot image header version 3 and 4)
Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Link: https://lore.kernel.org/r/20250625-abootimg_fix-v4-1-df7af00e87b0@linaro.org
[mkorpershoek: fixed trivial typo in commit msg]
Signed-off-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
diff --git a/cmd/abootimg.c b/cmd/abootimg.c
index 44de00f..6fb5215 100644
--- a/cmd/abootimg.c
+++ b/cmd/abootimg.c
@@ -96,7 +96,7 @@
 		return CMD_RET_USAGE;
 	struct andr_image_data img_data = {0};
 	const struct andr_boot_img_hdr_v0 *hdr;
-	const struct andr_vnd_boot_img_hdr *vhdr;
+	const struct andr_vnd_boot_img_hdr *vhdr = NULL;
 
 	hdr = map_sysmem(abootimg_addr(), sizeof(*hdr));
 	if (get_avendor_bootimg_addr() != -1)