include/linux/exportfs.h: drop duplicated word in a comment

Drop the doubled word "a" in a comment.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Link: http://lkml.kernel.org/r/c61b707a-8fd8-5b1b-aab0-679122881543@infradead.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/exportfs.h

@@ -178,7 +178,7 @@ struct fid {
  * get_name:
  *    @get_name should find a name for the given @child in the given @parent
  *    directory.  The name should be stored in the @name (with the
- *    understanding that it is already pointing to a a %NAME_MAX+1 sized
+ *    understanding that it is already pointing to a %NAME_MAX+1 sized
  *    buffer.   get_name() should return %0 on success, a negative error code
  *    or error.  @get_name will be called without @parent->i_mutex held.
  *