thermal/drivers/k3_j72xx_bandgap: Simplify code in k3_bgp_read_temp()

The return value of vtm_get_best_value() always >= 0, remove always
false expression 'dtemp < 0' in if statement.

Signed-off-by: Rex Nie <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Daniel Lezcano <[e-mail]>

drivers/thermal/k3_j72xx_bandgap.c

···
 		K3_VTM_TS_STAT_DTEMP_MASK;
 	dtemp = vtm_get_best_value(s0, s1, s2);
 
-	if (dtemp < 0 || dtemp >= TABLE_SIZE)
+	if (dtemp >= TABLE_SIZE)
 		return -EINVAL;
 
 	*temp = derived_table[dtemp];