fix(core1-control): Fix SysTick not being reset

Commit dbeec980 ("fix(pycardium): Fix delay implementation") enables
the systick on core 1 but on loading a new app, it is not reset which
makes some l0dables crash.  Fix this by always resetting (disabling) the
SysTick in the core1_reset() stub.

Fixes: dbeec980 ("fix(pycardium): Fix delay implementation")
Reported-by: Beastie <fischervincent98@gmail.com>
Signed-off-by: Rahix <rahix@rahix.de>