misc: Fix merge error in Makefile

commit 735a2da5 ("ANDROID: uid_sys_stats: rename uid_cputime.c
to uid_sys_stats.c") renamed the driver file along with the Kconfig
entry, however the resulting merge resolution failed to remove the
obj-$(CONFIG_UID_CPUTIME) target in the Makefile. Remove it.

Change-Id: I0b975e0c05b916a22dd7c226f1f6c0c8fa404323
Signed-off-by: Jack Pham <jackp@codeaurora.org>