checkpatch: don't warn about colon termination in linker scripts

This check erroneously flags cases like the one in my recent printk
enumeration patch[0], where the spaces are syntactic, and `section:' vs.
`section :' is syntactically important:

    ERROR: space prohibited before that ':' (ctx:WxW)
    torvalds#258: FILE: include/asm-generic/vmlinux.lds.h:314:
    +       .printk_fmts : AT(ADDR(.printk_fmts) - LOAD_OFFSET) {

0: https://lore.kernel.org/patchwork/patch/1375749/

Link: https://lkml.kernel.org/r/YBwhqsc2TIVeid3t@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

scripts/checkpatch.pl

@@ -5046,7 +5046,7 @@ sub process {
 				# A colon needs no spaces before when it is
 				# terminating a case value or a label.
 				} elsif ($opv eq ':C' || $opv eq ':L') {
-					if ($ctx =~ /Wx./) {
+					if ($ctx =~ /Wx./ and $realfile !~ m@.*\.lds\.h$@) {
 						if (ERROR("SPACING",
 							  "space prohibited before that '$op' $at\n" . $hereptr)) {
 							$good = rtrim($fix_elements[$n]) . trim($fix_elements[$n + 1]);