smb3: if max_channels set to more than one channel request multichannel

Mounting with "multichannel" is obviously implied if user requested
more than one channel on mount (ie mount parm max_channels>1).
Currently both have to be specified. Fix that so that if max_channels
is greater than 1 on mount, enable multichannel rather than silently
falling back to non-multichannel.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Cc: <stable@vger.kernel.org> # v5.11+
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>

Author: smfrench

fs/cifs/fs_context.c

@@ -1021,6 +1021,9 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 			goto cifs_parse_mount_err;
 		}
 		ctx->max_channels = result.uint_32;
+		/* If more than one channel requested ... they want multichan */
+		if (result.uint_32 > 1)
+			ctx->multichannel = true;
 		break;
 	case Opt_handletimeout:
 		ctx->handle_timeout = result.uint_32;