Squashed commit of the following:
boards/arm/s32k1xx/s32k148evb: Correct linker scripts for the S32K148, Update README files, Hook eht S32K148EVB into the configuration and build system.
arm/s32k1xx/s32k148evb: Verify core and peripheral clocking. It is the same as the S32K146EVB. Fixed one-too-many copy-paste error in both.
boards/arm/s32k1xx/s32k148evb: Correct LED and button pin number for the S32K148EVB.
boards/arm/s32k1xx/s32k148evb: Change all occurrences of 146 to 148.
boards/arm/s32k1xx/s32k148evb: Initial S32K148EVB. Initial commit is just clone of S32K146EVB with file name changes
arch/arm/src/s32k1xx/s32k1xx_lowputc.c: Fix a typo that prevented LPUART1 from working.
arch/arm/src/s32k1xx/s32k1xx_periphclocks.c and related files: Fix yet another case of confusion between pre-decremented and non-decremented divider values. Enforce the rule that dividers are not decremented until the moment they are written into registers.
arch/arm/src/s32k1xx/s32k1xx_clockconfig.c: Fix another problem related to whether a divider is pre-decremented or not. The answer must be the divder values are never pre-decremented. They are decremented just before being written to hardware.
arch/arm/src/s32k1xx/s32k1xx_clockconfig.c: Clean up some bad conditional logic. Precedence of operators problem.
boards/arm/s32k1xx/s32k118evb: Add support for execution out of SRAM. This is helpful for bringup when you want to avoid putting a lethal image in FLASH.
arch/arm/src/s32k1xx/s32k1xx_clockconfig.h: Remove crystal frequency, it is not used.
arch/arm/src/s32k1xx/s32k1xx_wdog.h: Fix a typo in a register name.i
boards/arm/s32k1xx/s32k*evb/configs/nsh/defconfig: Create Motorola SREC output format.
