LPC17xx, TIVA, and Kinetis interrupt initialization:  use the NVIC ICTR register to determine how many interrupt lines/registers are supported by the MCU

Move the un-definitions of __ramfuncs__ from the sam_clockconfig.c to the common up_internal.h header file so that the attribute will be applied the same to function definitions and prototypes.

SAMA5 TWI: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 SSC: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 EMAC/GMAC: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 CAN: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

SAMA5 ADC: If running from SDRAM, BOARD_MCK_FREQUENCY is not a constant and cannot be used in pre-processor conditionals

examples/touchscreen:  Add a configuration option to indicate that there is or is not an architecture-specific initialization function