KL25 DMA, DMAMUX, LLWU, ADC, LPTMR, TSI, MCG regs.

Added peripheral structures and register constants for KL25Z4 MCU
peripherals: DMA, DMAMUX, LLWU, ADC, LPTMR, TSI, and MCG.

Also, PORTx_PCRn_MUX(x) macro made the PIN_MUX_ALTERNATIVE(x) redundant.
Fixed PORTx register #define constants PRC -> PCR typo.