power: qpnp-smbcharger: fix the error in setting current_limit

Currently, the return code is checked wrongly to determine the
current_limit for USB chargers. This ends up in drawing only
100mA from SDP as against 500mA. Fix it.

CRs-Fixed: 867835
Change-Id: I365a2cfdd108a3da34bc309629451158f57b9318
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>