power: bq2415x_charger: Properly handle ENODEV from power_supply_get_by_phandle

The power_supply_get_by_phandle() on error returns ENODEV or NULL.
The driver later expects obtained pointer to power supply to be
valid or NULL. If it is not NULL then it dereferences it in
bq2415x_notifier_call() which would lead to dereferencing ENODEV-value
pointer.

Properly handle the power_supply_get_by_phandle() error case by
replacing error value with NULL. This indicates that usb charger
detection won't be used.

Fix also memory leak of 'name' if power_supply_get_by_phandle() fails
with NULL and probe should defer.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: faffd234 ("bq2415x_charger: Add DT support")
Cc: <stable@vger.kernel.org>
[small fix regarding the missing ti,usb-charger-detection info message]
Signed-off-by: Sebastian Reichel <sre@kernel.org>