unicore32: replace unicore32-specific iomap functions with generic lib implementation

1. define and enable CONFIG_GENERIC_IOMAP
2. define unicore32-specific PCI_IOBASE for asm-generic/io.h
3. define HAVE_ARCH_PIO_SIZE and unicore32-specific PIO_* macros
4. remove all unicore32-specific iomap functions

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Reviewed-and-Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/unicore32/mm/Makefile b/arch/unicore32/mm/Makefile
index f3ff410..46c1666 100644
--- a/arch/unicore32/mm/Makefile
+++ b/arch/unicore32/mm/Makefile
@@ -3,7 +3,7 @@
 #
 
 obj-y				:= extable.o fault.o init.o pgd.o mmu.o
-obj-y				+= iomap.o flush.o ioremap.o
+obj-y				+= flush.o ioremap.o
 
 obj-$(CONFIG_SWIOTLB)		+= dma-swiotlb.o