The RBC823 has only one NOR flash bank. Remove all code trying to
deal with a second bank. This also fixes a number of GCC 4.6 build
warnings:
flash.c: In function 'flash_init':
flash.c:62:12: warning: array subscript is above array bounds
[-Warray-bounds]
flash.c:63:12: warning: array subscript is above array bounds
[-Warray-bounds]
flash.c:66:12: warning: array subscript is above array bounds
[-Warray-bounds]