i2c: designware: fix reset handling on socfpga gen5

Using this driver on socfpga gen5 with DM_I2C enabled leads to a data abort
as the 'i2c' reset property cannot be found (the gen5 dtsi does not provide
reset-names).

The actual bug was to check 'if (&priv->reset_ctl)', which is never false.

While at it, convert the driver to use 'reset_get_bulk' instead of looking
at a specific named reset and also make it release the reset on driver
remove before starting the OS.

Fixes: 622597de ("i2c: designware: add reset ctrl to driver")
Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>