[sw/rom] Add EXPECT_SEC_WRITE_INCREMENT
[sw/rom] Add EXPECT_SEC_WRITE_INCREMENT

This commit adds EXPECT_SEC_WRITE_INCREMENT to the mock_sec_mmio module
to simplify the test interface.

Signed-off-by: Miguel Osorio <c7c97b215f812c2e8a32efd57ad5e976a6eb9e45@google.com>

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