Documentation: fpga: eliminate duplicated word

Drop the doubled word "this".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Wu Hao <hao.wu@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Wu Hao <hao.wu@intel.com>
Cc: linux-fpga@vger.kernel.org
Link: https://lore.kernel.org/r/20200707180414.10467-6-rdunlap@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/fpga/dfl.rst

@@ -8,7 +8,7 @@ Authors:
 - Xiao Guangrong <guangrong.xiao@linux.intel.com>
 - Wu Hao <hao.wu@intel.com>
 
-The Device Feature List (DFL) FPGA framework (and drivers according to this
+The Device Feature List (DFL) FPGA framework (and drivers according to
 this framework) hides the very details of low layer hardwares and provides
 unified interfaces to userspace. Applications could use these interfaces to
 configure, enumerate, open and access FPGA accelerators on platforms which