arm: socfpga: Fix with the correct polling on bit is set

Commit 2baa9972 ("arm: socfpga: Add FPGA driver support for Arria 10")
Polling on wrong cleared bit. Fix with correct polling on bit is set.

Fixes: 2baa9972

 ("arm: socfpga: Add FPGA driver support for Arria 10")

Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>