soc: arm: nxp_lpc: convert NXP LPC SOCs to use CMSIS SystemInit

Convert NXP LPC SOCs to use CMSIS SystemInit, and remove redundant code
where it exists. This will enable initialization flows to be more
standardized across all platforms.

Since LPC54xxx and LPC55xxx series enables SRAM banks in SystemInit,
provide Kconfigs to bypass this setting and keep additional SRAM
banks unclocked.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>