omap4: mux: Remove duplicate mux modes

Remove duplicate mux modes to make the binary smaller:

text    data     bss     dec     hex filename
9378   24472       0   33850    843a mux44xx.o
9378   19104       0   28482    6f42 mux44xx.o

Cc: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>