[fpv/keymgr] Fix keymgr prim_flop_sparse_fsm path
[fpv/keymgr] Fix keymgr prim_flop_sparse_fsm path

This PR removes a non-exist path for prim_flop_sparse_fsm in keymgr,
which causes compile error.

Signed-off-by: Cindy Chen <399ad771a111eac8923348b1e2af093034e5d4f1@google.com>

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