staging: fbtft: Convert int arrays to s16

staging: fbtft: Convert int arrays to s16

These arrays use -1, -2, and -3 as initiators for various types of
writes to initialize hardware.

No values are used that conflict with using these arrays as s16
instead of int and reducing overall data is good.

$ size drivers/staging/fbtft/built-in.o*
   text	   data	    bss	    dec	    hex	filename
 116120	  32872	   4152	 153144	  25638	drivers/staging/fbtft/built-in.o.new
 116104	  36344	   6200	 158648	  26bb8	drivers/staging/fbtft/built-in.o.old

Miscellaneous:

o Realign some of the arrays to make reading a bit easier

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>