microblaze: fix typo in a comment

The double `was' is repeated in a comment. Consequently, remove one
`was' from the comment.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Link: https://lore.kernel.org/r/20211128034823.6930-1-wangborong@cdjrlc.com


Signed-off-by: Michal Simek <michal.simek@xilinx.com>