driver/arm/css: minor bug fix

The cpu index was wrongly checked causing it to assert always.
Since this code path is exercised only during TF test "NODE_HW_STAT",
which queries Power state from SCP, this bug was not detected earlier.

Change-Id: Ia25cef4c0aa23ed08092df39134937a2601c21ac
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>

drivers/arm/css/scp/css_pm_scmi.c

@@ -224,8 +224,8 @@ void css_scp_on(u_register_t mpidr)
 
 	SCMI_SET_PWR_STATE_MAX_PWR_LVL(scmi_pwr_state, lvl - 1);
 
-	core_pos = plat_core_pos_by_mpidr(mpidr);
-	assert(core_pos >= 0 && (core_pos < PLATFORM_CORE_COUNT));
+	core_pos = (unsigned int)plat_core_pos_by_mpidr(mpidr);
+	assert(core_pos < PLATFORM_CORE_COUNT);
 
 	css_scp_core_pos_to_scmi_channel(core_pos, &domain_id,
 			&channel_id);
@@ -256,8 +256,8 @@ int css_scp_get_power_state(u_register_t mpidr, unsigned int power_level)
 		return PSCI_E_INVALID_PARAMS;
 	}
 
-	cpu_idx = plat_core_pos_by_mpidr(mpidr);
-	assert(cpu_idx > -1);
+	cpu_idx = (unsigned int)plat_core_pos_by_mpidr(mpidr);
+	assert(cpu_idx < PLATFORM_CORE_COUNT);
 
 	css_scp_core_pos_to_scmi_channel(cpu_idx, &domain_id, &channel_id);
 	ret = scmi_pwr_state_get(scmi_handles[channel_id],