selftests/powerpc/papr-vpd: Fix missing variable initialization

The "close handle without consuming VPD" testcase has inconsistent
results because it fails to initialize the location code object it
passes to ioctl() to create a VPD handle. Initialize the location code
to the empty string as intended.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Fixes: 9118c5d ("powerpc/selftests: Add test for papr-vpd")
Reported-by: Geetika Moolchandani <geetika@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240404-papr-vpd-test-uninit-lc-v2-1-37bff46c65a5@linux.ibm.com

tools/testing/selftests/powerpc/papr_vpd/papr_vpd.c

@@ -154,7 +154,7 @@ static int dev_papr_vpd_null_handle(void)
 static int papr_vpd_close_handle_without_reading(void)
 {
 	const int devfd = open(DEVPATH, O_RDONLY);
-	struct papr_location_code lc;
+	struct papr_location_code lc = { .str = "", };
 	int fd;
 
 	SKIP_IF_MSG(devfd < 0 && errno == ENOENT,