soc: sam0: Speed-up xosc32 initialization

The current selected start-up time takes 8 seconds to initialize.
When xosc32 is used as main clock reference it blocks the whole
initializarion of the system by that amount of time. This patch
relax that condition setting the initialization time to 62ms.

Fixes #79949

Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>