xtensa: 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: Chris Zankel <chris@zankel.net>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/xtensa/include/asm/io.h

@@ -74,13 +74,6 @@ static inline void iounmap(volatile void __iomem *addr)
 
 #endif /* CONFIG_MMU */
 
-/*
- * Generic I/O
- */
-#define readb_relaxed readb
-#define readw_relaxed readw
-#define readl_relaxed readl
-
 #endif	/* __KERNEL__ */
 
 #include <asm-generic/io.h>