If sockets were open when calling soft reset, gc_sweep_all() would try to
close them. In case of e.g. the NINA WiFi handler, connected through SPI,
spi_transfer() would be called for command exchange with the NINA module.
But at that time SerCom was already disabled.
Moving sercom_deinit_all() behind gc_sweep_all() solves this issue.
Signed-off-by: robert-hh <robert@hammelrath.com>