ddr: socfpga: Clean up EMIF reset

ddr: socfpga: Clean up EMIF reset

The EMIF reset code can well use wait_for_bit_le32() instead of all that
convoluted polling code. Reduce the timeout from 100 seconds to 1 second,
since if the EMIF fails to reset itself in 1 second, it's unlikely longer
wait would help. Make sure to clear the EMIF reset request even if the
SEQ2CORE_INT_RESP_BIT isn't asserted.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <chin.liang.see@intel.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Cc: Tien Fong Chee <tien.fong.chee@intel.com>