alpha: add io{read,write}{16,32}be functions

These functions are used in some PCI drivers with big-endian
MMIO space.

Admittedly it is almost certain that no one this side of the
Moon would use such a card in an Alpha but it does get us
closer to being able to build allyesconfig or allmodconfig,
and it enables the Debian default generic config to build.
Tested-by: NRaúl Porcel <armin76@gentoo.org>
Signed-off-by: NMichael Cree <mcree@orcon.net.nz>
Signed-off-by: NMatt Turner <mattst88@gmail.com>

arch/alpha/include/asm/io.h

@@ -489,6 +489,11 @@ extern inline void writeq(u64 b, volatile void __iomem *addr)
 }
 #endif
 
+#define ioread16be(p) be16_to_cpu(ioread16(p))
+#define ioread32be(p) be32_to_cpu(ioread32(p))
+#define iowrite16be(v,p) iowrite16(cpu_to_be16(v), (p))
+#define iowrite32be(v,p) iowrite32(cpu_to_be32(v), (p))
+
 #define inb_p		inb
 #define inw_p		inw
 #define inl_p		inl