cappuccino/lsu: stay in WRITE state on store_buffer_write

Apart from being one clock cycle faster, this also avoids connecting
the (potentially critical) dbus_ack_i signal to the read enable
input of the store buffer.

In addition to that it also fixes a bug where the lsu_valid
signal would be detached from the storebuffer logic when
the state machine would transition from WRITE->IDLE->WRITE.
lsu: reset state for write pending

Define the store_buffer_write_pending signal to be low after reset.
lsu: add missing signal definition

dc_refill_req was not properly defined if the cache is deactivated.
cappuccino/ctrl: do not copy FO from esr on rfe

The FO (fixed one) bit should always be set to one,
allowing it to be altered through esr is not allowed.