ARM: OMAP7XX: Remove omap730.h and omap850.h

No file includes omap730.h or omap850.h. That's not surprising, as
commit e6684f71 ("OMAP7XX: Create
omap7xx.h") created a header that was "intended to replace omap730.h and
omap850.h", while all "values defined [in omap7xx.h] are identical to
those in both the old files". So it seems it was just an oversight to
keep both the old files after commit
7a8f48f8 ("OMAP7XX: omap_uwire.c:
Convert to omap7xx.h") converted the last file still including one of
those two old files.

Convert the last reference to omap730.h to a reference to omap7xx.h too.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Tony Lindgren <tony@atomide.com>