STM32 DAC: Fix DMA support for STM32F2xxx and STM32F4xxx

STM32L4: Fix incorrect and conflicting definitions for STM32L4_NGPIOS and STM32L4_NGPIO_PORTS.  Now there is only STM32L4_NPORTS.

SAMV7 USB:  Fix a DMA related issue.  When DMA completes with NBUSYBK greater than zero, need to way for NBUSYBK interrupt.

i.MX6: Hmm.. I think the i.MX6 Solo Lite has global and private timers.  Note cleare from the reference manual

i.MX6: Revamp GIC initialization logic; add missing register bit definitions and initialization of GIC control register for secure cases

Rename CONFIG_SAMA5_HAVE_TRUSTZONE to CONFIG_ARCH_HAVE_TRUSTZONE; Eliminate CONFIG_SAMA5_SECURE; Add CONFIG_ARCH_TRUSTZONE_SECURE

MPCore: Fix missing header file inclusion; Add GIC-based implementations of up_enabable_irq(0 and up_disable_irq()