ARM: mx27_defconfig: enable switches used in mx27 code

- enable all mx27 machines (MACH_CPUIMX27, MACH_IMX27_VISSTRIM_M10,
  MACH_PCA100, MACH_MXT_TD60) including optional features for
  CPUIMX27
- eukrea_mbimx27-baseboard.c uses TOUCHSCREEN_ADS7846
- mach-cpuimx27.c uses SERIAL_8250
- several machines make use of SPI_IMX (selects SPI_BITBANG)
- drop VGA_CONSOLE as this isn't selectable anymore since fb78b51cb11e
- several machines make use of USB_ULPI (depends on USB, but don't
  enable USB_DEVICE_CLASS as it's deprecated)

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>