mxs: prefix register structs with 'mxs' prefix

arch/arm/cpu/arm926ejs/mxs/clock.c

arch/arm/cpu/arm926ejs/mxs/mx28.c

arch/arm/cpu/arm926ejs/mxs/spl_lradc_init.c

arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c

arch/arm/cpu/arm926ejs/mxs/spl_power_init.c

arch/arm/cpu/arm926ejs/mxs/timer.c

arch/arm/include/asm/arch-mxs/regs-apbh.h

arch/arm/include/asm/arch-mxs/regs-bch.h

arch/arm/include/asm/arch-mxs/regs-clkctrl.h

arch/arm/include/asm/arch-mxs/regs-digctl.h

arch/arm/include/asm/arch-mxs/regs-gpmi.h

arch/arm/include/asm/arch-mxs/regs-i2c.h

arch/arm/include/asm/arch-mxs/regs-lcdif.h

arch/arm/include/asm/arch-mxs/regs-lradc.h

arch/arm/include/asm/arch-mxs/regs-ocotp.h

arch/arm/include/asm/arch-mxs/regs-pinctrl.h

arch/arm/include/asm/arch-mxs/regs-power.h

arch/arm/include/asm/arch-mxs/regs-rtc.h

arch/arm/include/asm/arch-mxs/regs-ssp.h

arch/arm/include/asm/arch-mxs/regs-timrot.h