power: smb349-charger: make the battery capacity writeable
power: smb349-charger: make the battery capacity writeable

There are some applications that may want to fake a battery state of
charge (SoC). To standarize this on different devices, make the battery
power supply capacity property writeable.

Change-Id: I0db3b2d7442330ce5fc80aa4dae65c7270b513b8
Signed-off-by: Xiaozhe Shi <4c58d9c21c42c2a4cf34b559441bd01b9c143cf4@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas