Doc: Docbook/iio: Fix typo in iio.tmpl

This patch fix a spelling typo in iio.tmpl.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/DocBook/iio.tmpl

@@ -458,7 +458,7 @@
             .scan_type = {
               .sign = 's',
               .realbits = 12,
-              .storgebits = 16,
+              .storagebits = 16,
               .shift = 4,
               .endianness = IIO_LE,
             },