[sw/runtime] Fix ibex_timeout_check
[sw/runtime] Fix ibex_timeout_check

The return value should match the function documentation.
Fix the IBEX_SPIN_FOR macro to match.

Signed-off-by: Guillermo Maturana <085716c7110d3f31793f7d964c2e5fd26da1c550@google.com>

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