Drivers: hv: vmus: Fix the check for return value from kmsg get dump buffer

The code to support panic control message was checking the return was
checking the return value from kmsg_dump_get_buffer as error value, which
is not what the routine returns. This fixes it.

Fixes: 81b18bce ("Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic")
Signed-off-by: NSunil Muthuswamy <sunilmut@microsoft.com>
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/vmbus_drv.c

@@ -1047,12 +1047,9 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper,
 	 * Write dump contents to the page. No need to synchronize; panic should
 	 * be single-threaded.
 	 */
-	if (!kmsg_dump_get_buffer(dumper, true, hv_panic_page,
-				  PAGE_SIZE, &bytes_written)) {
-		pr_err("Hyper-V: Unable to get kmsg data for panic\n");
-		return;
-	}
-
+	kmsg_dump_get_buffer(dumper, true, hv_panic_page, PAGE_SIZE,
+			     &bytes_written);
+	if (bytes_written)
 		hyperv_report_panic_msg(panic_pa, bytes_written);
 }