ocf/ctx: Fix warning of using uninitialized value.

Warning:
ctx.c: In function ‘vbdev_ocf_ctx_log_printf’:
ctx.c:503:2: warning: ‘spdk_lvl’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  503 |  spdk_vlog(spdk_lvl, NULL, -1, NULL, fmt, args);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compiling with ocf module, here should add default.

Signed-off-by: yidong0635 <dongx.yi@intel.com>
Change-Id: I645a1044e58b63d5a58fde19baa3c125f97e0a7b
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/2603
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>

module/bdev/ocf/ctx.c

@@ -497,6 +497,7 @@ vbdev_ocf_ctx_log_printf(ocf_logger_t logger, ocf_logger_lvl_t lvl,
 
 	case log_info:
 	case log_debug:
+	default:
 		spdk_lvl = SPDK_LOG_INFO;
 	}