i2c: cadence: Avoid fifo clear after start

The Driver unintentionally programs ctrl reg to clear the fifo, which
happens after the start of transaction. Previously, this was not an issue
as it involved read-modified-write. However, this issue breaks i2c reads
on QEMU, as i2c-read is executed before guest starts programming control
register.

Fixes: ff0cf7bc ("i2c: cadence: Remove unnecessary register reads")
Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@amd.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>