soc: silabs: Update HAL for Series 2

Update HAL for Series 2 devices to Simplicity SDK 2024.6.

This HAL deprecates sl_device_init_emu(). Equivalent functions
are now performed by sl_power_manager_init().

For now, soc.c remains compatible with both the Gecko SDK based
HAL for Series 0 and 1, and the Simplicity SDK based HAL for
Series 2. In a future commit, soc.c will be split between the
two platforms.

Signed-off-by: Aksel Skauge Mellbye <aksel.mellbye@silabs.com>