Get rid of broken optimization in MicroWire driver:  don't try to morph
consecutive single-byte operations into one (faster) two-byte operation.
This resolves some byteswap problems.  (And consequently allows fixing
some bugs in at least the OMAP version of the ads7846 driver...)

Also, reject LSB-first device modes; this controller doesn't support them.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>