x86/io: Remove mem*io() duplications

Generic header defines memset_io, memcpy_fromio(). and memcpy_toio().

Reuse them from generic header and remove in x86 code.
Move the descriptions to the generic header as well.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Baolin Wang <baolin.wang@spreadtrum.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-i2c@vger.kernel.org
Cc: wsa@the-dreams.de
Link: http://lkml.kernel.org/r/20170630170934.83028-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 7ef015e..395afc8 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -954,6 +954,14 @@ static inline void *bus_to_virt(unsigned long address)
 
 #ifndef memset_io
 #define memset_io memset_io
+/**
+ * memset_io	Set a range of I/O memory to a constant value
+ * @addr:	The beginning of the I/O-memory range to set
+ * @val:	The value to set the memory to
+ * @count:	The number of bytes to set
+ *
+ * Set a range of I/O memory to a given value.
+ */
 static inline void memset_io(volatile void __iomem *addr, int value,
 			     size_t size)
 {
@@ -963,6 +971,14 @@ static inline void memset_io(volatile void __iomem *addr, int value,
 
 #ifndef memcpy_fromio
 #define memcpy_fromio memcpy_fromio
+/**
+ * memcpy_fromio	Copy a block of data from I/O memory
+ * @dst:		The (RAM) destination for the copy
+ * @src:		The (I/O memory) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data from I/O memory.
+ */
 static inline void memcpy_fromio(void *buffer,
 				 const volatile void __iomem *addr,
 				 size_t size)
@@ -973,6 +989,14 @@ static inline void memcpy_fromio(void *buffer,
 
 #ifndef memcpy_toio
 #define memcpy_toio memcpy_toio
+/**
+ * memcpy_toio		Copy a block of data into I/O memory
+ * @dst:		The (I/O memory) destination for the copy
+ * @src:		The (RAM) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data to I/O memory.
+ */
 static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer,
 			       size_t size)
 {