reg_sensor: Update assertions
Created by: nicola-mazzucato-arm
This patch updates the assertions used in the module to make proper use of the up-to-date fwk_assert.
Change-Id: I3f57374bc054cfcc1cd2cd0247f10e52f9a4eb3e Signed-off-by: Nicola Mazzucato nicola.mazzucato@arm.com