[PATCH] ads7846 conversion accuracy

This improves accuracy of the touchscreen and hwmon sensor readings,
addressing an issue noted by Imre Deak: there's an extra bit written before
the sample (12 bits) gets written out.

It also catches up to various comments, and makes the /proc/interrupts
entry sensible again.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Imre Deak <imre.deak@nokia.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Dmitry Torokhov <dtor_core@ameritech.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>