asm-generic headers: uaccess.h to conditionally define segment_eq()

This is because mm_segment_t is exported by arch code, while seqment_eq
assumes it will have .seg element.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

include/asm-generic/uaccess.h

@@ -7,7 +7,6 @@
  * address space, e.g. all NOMMU machines.
  */
 #include <linux/sched.h>
-#include <linux/mm.h>
 #include <linux/string.h>
 
 #include <asm/segment.h>
@@ -32,7 +31,9 @@ static inline void set_fs(mm_segment_t fs)
 }
 #endif
 
+#ifndef segment_eq
 #define segment_eq(a, b) ((a).seg == (b).seg)
+#endif
 
 #define VERIFY_READ	0
 #define VERIFY_WRITE	1