arm: mach-k3: am642: Fix reset for workaround errata ID i2331

To workaround an issue in AM642 we reset the SoC in early boot. For that
we first probed the sysreset driver by calling uclass_get_device(). The
ti-sci sysreset driver is now probed during the ti-sci firmware probe.
Update this call to probe the firmware driver which will then probe
the sysreset driver allowing do_reset() to again function as expected.

Reported-by: Jonathan Humphreys <j-humphreys@ti.com>
Fixes: fc5d4028 ("firmware: ti_sci: Bind sysreset driver when enabled")
Signed-off-by: Andrew Davis <afd@ti.com>
Tested-by: Wadim Egorov <w.egorov@phytec.de>
Tested-by: Kamlesh Gurudasani <kamlesh@ti.com>