arch: nxp: lpc54xxx: Rename SoC bits from LPC54114 to LPC54114_M4

Rename various SoC related defines and files from just being LPC54114
to LPC54114_M4.  This is in prep for supporting a build for the second
core on the LPC54114 (the Cortex-M0+).

* Renamed Kconfig SOC_LPC54114 to SOC_LPC54114_M4
* Renamed Kconfig.defconfig.lpc54114 to Kconfig.defconfig.lpc54114_m4
* Introduced nxp_lpc54xxx_m4.dtsi based on nxp_lpc54xxx.dtsi
* Moved some pinmux related defines into SoC code.

Signed-off-by: Stanislav Poboril <stanislav.poboril@nxp.com>
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>