ARM: imx8m: Do not define do_reset() if sysreset is enabled

ARM: imx8m: Do not define do_reset() if sysreset is enabled

The SPL can also be compiled with sysreset drivers just fine, so
update the condition to cater for that option.

Signed-off-by: Marek Vasut <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Flavio Suligoi <[email protected]>
Cc: Harald Seiler <[email protected]>
Cc: Igor Opaniuk <[email protected]>
Cc: Marcel Ziswiler <[email protected]>
Cc: Oleksandr Suvorov <[email protected]>
Cc: Peng Fan <[email protected]>
Cc: Stefano Babic <[email protected]>