regulator: tps65218: Fix strobe assignment

Currentlly tps_info structure is no longer used. So use the
strobes parameter in tps65218 structure to capture the info.

Fixes: 2dc49403

 (regulator: tps65218: Remove all the compatibles)
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>