bxe: tag files to skip clang-format formatting

bxe contains three files which are sets of constants or other data, and
might be auto-generated or have an upstream.  They are rather large
files and clang-format takes quite some time when run against them, so
just skip formatting.

MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D27806

sys/dev/bxe/57710_init_values.c

@@ -28,7 +28,7 @@
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
-
+/* clang-format off */
 
 /*
 * This file contains an array of operations needed to initialize the chip:

sys/dev/bxe/57711_init_values.c

@@ -28,7 +28,7 @@
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
-
+/* clang-format off */
 
 /*
 * This file contains an array of operations needed to initialize the chip:

sys/dev/bxe/57712_init_values.c

@@ -28,7 +28,7 @@
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
-
+/* clang-format off */
 
 /*
 * This file contains an array of operations needed to initialize the chip: