Staging: panel: major checkpatch cleanup

All of the 401 errors, and 108 of the 235 warnings reported by checkpatch
were cleared. The only remanining warnings left concern lines larger than
80 characters. This cleanup will be performed last.
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Cc: Frank Menne <frank.menne@hsm.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>