dt-bindings: bus: ti-sysc: resync with Linux 5.9-rc7

Add support for PRUSS SYSC type:
The PRUSS module has a SYSCFG which is unique. The SYSCFG has two
additional unique fields called STANDBY_INIT and SUB_MWAIT in addition
to regular IDLE_MODE and STANDBY_MODE fields. Add the bindings for this
new sysc type.

Add support for MCAN on dra76x:
The dra76x MCAN generic interconnect module has a its own format for the
bits in the control registers.

Signed-off-by: Dario Binacchi <dariobin@libero.it>