remove <linux/i2c/twl4030-pwrirq.h>

Get rid of another needless TWL header file:  twl4030-pwrirq.h
can easily live in twl4030.h; updating its three users.

Also switch to the shared definition of the SIH_CTRL COR bit,
remove useless-to-non-driver MODULE_ALIAS(), and add a note
about a bug that will appear if anyone ever removes this code.

No functional changes, just shrinkage.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>