hw/pxa2xx_lcd.c: drop target_phys_addr_t usage in device state

Pxa2xx LCD controller is intended to work with 32-bit bus and it has no knowledge
of system's physical address size, so it should not use target_phys_addr_t in it's
state. Convert three variables in DMAChannel state from target_phys_addr_t to uint32_t,
use VMSTATE_UINT32 instead of VMSTATE_UINTTL for these variables.
We can do this safely because:
1) pxa2xx has 32-bit physical address;
2) rest of the code in file never assumes converted variables to have any size
different from uint32_t;
3) we shouldn't have used VMSTATE_UINTTL in the first place because this macro
is for target_ulong type (which can be different from target_phys_addr_t).

Signed-off-by: Igor Mitsyanko <i.mitsyanko@samsung.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>