kobject: increase number of kobject uevent pointers to 64

Power supply framework uses uevents to notify the power supply
change events to the userspace. Some power supplies have their
properties increasing thus overflowing the number of kobject
uevent pointers, triggering warning shown below.

[   10.577545] WARNING: CPU: 3 PID: 406 at kernel/lib/kobject_uevent.c:393 add_uevent_var+0xc0/0x100()
[   10.589680] add_uevent_var: too many keys
[   10.593809] Modules linked in:
[   10.596686] CPU: 3 PID: 406 Comm: kworker/3:2 Tainted: G        W      3.18.20-g5e99605-00057-gd18285f #603
[   10.606373] Hardware name: Qualcomm Technologies, Inc. MSM 8996 v3 + PMI8996 MTP (DT)
[   10.614188] Workqueue: events power_supply_changed_work
[   10.619366] Call trace:
[   10.621803] [<ffffffc00008881c>] dump_backtrace+0x0/0x130
[   10.627175] [<ffffffc00008895c>] show_stack+0x10/0x1c
[   10.632237] [<ffffffc000cc4d00>] dump_stack+0x74/0xb8
[   10.637253] [<ffffffc0000a0fec>] warn_slowpath_common+0x90/0xb8
[   10.643170] [<ffffffc0000a1060>] warn_slowpath_fmt+0x4c/0x58
[   10.648814] [<ffffffc00031121c>] add_uevent_var+0xbc/0x100
[   10.654259] [<ffffffc0003116f8>] kobject_uevent_env+0x498/0x5a8
[   10.660185] [<ffffffc000311814>] kobject_uevent+0xc/0x18
[   10.665457] [<ffffffc0007fd3c0>] power_supply_changed_work+0xb0/0xf0
[   10.671830] [<ffffffc0000b617c>] process_one_work+0x23c/0x3f4
[   10.677529] [<ffffffc0000b7338>] worker_thread+0x280/0x3a8
[   10.683017] [<ffffffc0000bb384>] kthread+0xe0/0xec

Fix this warning by increasing the number of kobject uevent
pointers from 32 to 64.

CRs-Fixed: 971954
Change-Id: Ide942d25006abd36ba7be945be397a535e91d970
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>