checkpatch: add test for long udelay

Holger reported:

: The macro udelay cannot handle large values because of loss-of-precision.
:
: IMHO udelay on ARM is broken, because it also cannot work with fast
: ARM processors (where bogomips >= 3355, which is in sight now). It's
: just not broken enough that someone did something against it ...   so
: the current kludge is good enough.

Until then, warn on long udelay uses.

Also fix uses of $line that should have been $herecurr.

Signed-off-by: Joe Perches <joe@perches.com>
Reported-by: Holger Schurig <holgerschurig@gmail.com>
Cc: Sujith Manoharan <sujith@msujith.org>
Cc: John Linville <linville@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>