lib: bitmap: delete duplicated words

Drop the repeated word "an".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200823040424.25760-1-rdunlap@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/bitmap.c

@@ -23,7 +23,7 @@
 /**
  * DOC: bitmap introduction
  *
- * bitmaps provide an array of bits, implemented using an an
+ * bitmaps provide an array of bits, implemented using an
  * array of unsigned longs.  The number of valid bits in a
  * given bitmap does _not_ need to be an exact multiple of
  * BITS_PER_LONG.