[entropy_src/rtl] fix config bits for route to sw reg
[entropy_src/rtl] fix config bits for route to sw reg

There are some configuration bits that need to route seeds to a sw register.
Also if disabled, the register should not be allowed to be read.
This change fixes any unexpected behavior regarding seed routing.

Signed-off-by: Mark Branstad <d7ca710cc6ec5dc810c866dae5369b19445fbeef@wdc.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan