spi: img-spfi: Remove udelay in soft reset

Removing the udelay between setting and clearing the soft reset bit in
the spfi control register as it is not required.

Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com>
Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>