s390: io: remove dummy relaxed accessor macros for reads

These are now defined by asm-generic/io.h, so we don't need the private
definitions anymore.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/s390/include/asm/io.h

@@ -60,11 +60,6 @@ static inline void iounmap(volatile void __iomem *addr)
 #define __raw_writel	zpci_write_u32
 #define __raw_writeq	zpci_write_u64
 
-#define readb_relaxed	readb
-#define readw_relaxed	readw
-#define readl_relaxed	readl
-#define readq_relaxed	readq
-
 #endif /* CONFIG_PCI */
 
 #include <asm-generic/io.h>