cpu/arm/k60: Move 1-wire configuration to platform config-board.h

 - Use UART0 by default (AH T1.8 Wheel Loader uses this port)
 - Added ONEWIRE_* macros to platform/mulle/config-board.h
 - Make ow_init use port_module_enable() instead of direct register
   manipulation.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
cpu/arm/k60: Add clock_delay_usec for microsecond busy wait.

clock_delay_usec uses the PIT module as a wait timer. The length of the
wait is only approximate because of overhead and inexact target time
computations.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
cpu/arm/k60: power-modes: Add conditional sleep.

COND_WAIT, COND_STOP, COND_LLS, COND_VLPS will enter the specified mode
as long as the condition is true. Useful for waiting for I/O operations
to finish.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
cpu/arm/k60: implement generic SPI bus driver.

 - Only Master mode is supported for now.
 - Create SPI bus driver API.
 - SPI bus hardware driver in spi.c
 - Configuration is in config-board.h

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
platform/mulle: Flash use spi driver.

 - Uses new SPI driver in cpu/arm/k60
 - Remove unnecessary disabling of interrupts in xmem.

Flash memory access is already protected inside flash.c by
spi_acquire_bus/spi_release_bus.

Interrupts must not be disabled when calling spi_transfer_blocking
since that will wait for an IRQ driven transfer to finish.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
platform/mulle: Use spi driver for lis3dh.

LIS3DH is now using SPI driver in cpu/arm/k60.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
[SQUASH ME] fix comments on spi.h

 - Rename spi_arch.h -> spi-k60.h
 - Create spi-config.h
 - Rename spi_init() -> board_spi_init()
 - Remove all inclusion of spi.h
[SQUASH ME] Remove unused spi_transfer_sync_t
[SQUASH ME] Mulle flash: cleanup, remove unused cruft.
[SQUASH ME] platform/mulle: Update flash driver after comments from @scrizt.
[SQUASH ME] platform/mulle: Remove lis3dh_arch_init()