docs: powerpc: Fix a typo

s/struture/structure/
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20210322062237.2971314-1-unixbhaskar@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/powerpc/firmware-assisted-dump.rst

@@ -171,7 +171,7 @@ that were present in CMA region::
                                            (meta area)    |
                                                           |
                                                           |
-                      Metadata: This area holds a metadata struture whose
+                      Metadata: This area holds a metadata structure whose
                       address is registered with f/w and retrieved in the
                       second kernel after crash, on platforms that support
                       tags (OPAL). Having such structure with info needed