tty: Fix width of unsigned long bitfield padding

tty: Fix width of unsigned long bitfield padding

Commit 1c70f2cf581a16838ee292bb6d2e07a1778a18d1,
'tty: Serialize tcflow() with other tty flow control changes' and
commit 393a0396b977f3a3e22fe31336363ef8b6821ac0,
'tty: Workaround Alpha non-atomic byte storage in tty_struct' work around
compiler bugs and non-atomic storage on multiple arches by padding
bitfields out to the declared type which is unsigned long. However, the
width varies by arch.

Pad bitfields to actual width of unsigned long (which is BITS_PER_LONG).

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>