ARM: pxa: add defconfig covering all the boards

Add a defconfig covering all known pxa board, ie. all selectable machine
files in arch/arm/mach-pxa/*.c.

This defconfig was built by doing :
 - aggregation of all known defconfigs by cat
	am200epdkit_defconfig
	cm_x2xx_defconfig
	cm_x300_defconfig
	colibri_pxa270_defconfig
	colibri_pxa300_defconfig
	corgi_defconfig
	em_x270_defconfig
	eseries_pxa_defconfig
	ezx_defconfig
	h5000_defconfig
	imote2_defconfig
	lpd270_defconfig
	lubbock_defconfig
	magician_defconfig
	mainstone_defconfig
	multi_v7_defconfig
	palmz72_defconfig
	pcm027_defconfig
	pxa255-idp_defconfig
	pxa3xx_defconfig
	raumfeld_defconfig
	spitz_defconfig
	trizeps4_defconfig
	viper_defconfig
	xcep_defconfig
	zeus_defconfig
 - manual make menuconfig to ensure :
   - all pxa implementation were selected
   - all drivers were transformed into modules rather than builtin
     => as a consequence this single kernel will rely on an initramfs
     => as kernel size matters on pxa, each machine can take the subset
        of modules required for it to work
   - all missed configurations are selected verified by :
     => grep -i pxa .config | grep "is not set"
     => this should only show the left on purpose options (either not
        selectable or sharpsl exception below)
 - CONFIG_PXA_SHARPSL was disabled
   This breaks the boot very early on any non Sharp platform, see
   head-sharpsl.S

This defconfig was tested as booting up to the login phase on :
 - lubbock (pxa25x)
 - mainstone (pxa27x)
 - zylonite (pxa3xx)

The completion of this work will require to :
 - parse manually all the arch/arm/mach-pxa/*c files, look for all
   platform devices added, and verify they are all in pxa_defconfig
 - do the same to ensure all pxa specific drivers (leds, gpio, ...) are
   included
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>