checkpatch: improve space before tab --fix option

This test should remove all the spaces before a tab not just one space.

Substitute a tab for each 8 space block before a tab and remove less than
8 spaces before a tab.

This SPACE_BEFORE_TAB test is done after CODE_INDENT.

If there are spaces used at the beginning of a line that should be
converted to tabs, please make sure that the CODE_INDENT test and
conversion is done before this SPACE_BEFORE_TAB test and conversion.
Reported-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2118,8 +2118,10 @@ sub process {
 			if (WARN("SPACE_BEFORE_TAB",
 				"please, no space before tabs\n" . $herevet) &&
 			    $fix) {
-				$fixed[$linenr - 1] =~
-				    s/(^\+.*) +\t/$1\t/;
+				while ($fixed[$linenr - 1] =~
+					   s/(^\+.*) {8,8}+\t/$1\t\t/) {}
+				while ($fixed[$linenr - 1] =~
+					   s/(^\+.*) +\t/$1\t/) {}
 			}
 		}