unicore32 machine related: add frame buffer driver for pkunity-v3 soc

change from original version -- by advice of Paul Mundt
1. remove videomemorysize definitions
2. remove unifb_enable and unifb_setup
3. use dev_warn instead of printk in fb driver
4. remove judgement for FB_ACCEL_PUV3_UNIGFX
5. adjust clk_get and clk_set_rate calls
6. add resources definitions
7. remove unifb_option
8. adjust register for platform_device
9. adjust unifb_ops position and unifb_regs assignment position

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Arnd Bergmann <arnd@arndb.de>