staging: hikey9xx: hi6421v600-regulator: fix get_optimum_mode

During the driver refactor, a regression broke the logic inside
hi6421_spmi_regulator_get_optimum_mode(). Basically, if a LDO
has eco_uA == 0, it doesn't support economic mode. So, it should
return REGULATOR_MODE_NORMAL.

If economic mode is supported, it can return either
REGULATOR_MODE_IDLE or REGULATOR_MODE_NORMAL, depending on the
load current.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/f087981eb695eaab8c301c42977a4aa884affbbf.1611212783.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/hikey9xx/hi6421v600-regulator.c

@@ -206,7 +206,7 @@ hi6421_spmi_regulator_get_optimum_mode(struct regulator_dev *rdev,
 {
 	struct hi6421_spmi_reg_info *sreg = rdev_get_drvdata(rdev);
 
-	if (load_uA || ((unsigned int)load_uA > sreg->eco_uA))
+	if (!sreg->eco_uA || ((unsigned int)load_uA > sreg->eco_uA))
 		return REGULATOR_MODE_NORMAL;
 
 	return REGULATOR_MODE_IDLE;