ARM: ixp4xx: fix read{b,w,l} return types

On ixp4xx, the readl() function returns an 'unsigned long' output
when indirect I/O is used. This is unlike any other platform, and
it causes lots of harmless compiler warnings, such as:

drivers/ata/libahci.c: In function 'ahci_show_host_version':
drivers/ata/libahci.c:254:22: warning: format '%x' expects argument of type 'unsigned int', but argument 3 has type 'long unsigned int' [-Wformat=]
drivers/block/mtip32xx/mtip32xx.c: In function 'mtip_hw_read_registers':
drivers/block/mtip32xx/mtip32xx.c:2602:31: warning: format '%X' expects argument of type 'unsigned int', but argument 3 has type 'long unsigned int' [-Wformat=]
drivers/block/cciss.c: In function 'print_cfg_table':
drivers/block/cciss.c:3845:25: warning: format '%d' expects argument of type 'int', but argument 4 has type 'long unsigned int' [-Wformat=]

This changes all six of the ixp4xx specific I/O read functions
to return the same types that we have in the normal asm/io.h,
to avoid the warnings.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Krzysztof Halasa <khalasa@piap.pl>