percpu-refcount: Add percpu-refcount.o to obj-y

Drop percpu_ida.o from lib-y since it is also listed in obj-y
and it doesn't need to be listed in both places.

Move percpu-refcount.o from lib-y to obj-y to fix build errors
in target_core_mod:

ERROR: "percpu_ref_cancel_init" [drivers/target/target_core_mod.ko] undefined!
ERROR: "percpu_ref_kill_and_confirm" [drivers/target/target_core_mod.ko] undefined!
ERROR: "percpu_ref_init" [drivers/target/target_core_mod.ko] undefined!
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

lib/Makefile

@@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
-	 earlycpio.o percpu-refcount.o percpu_ida.o
+	 earlycpio.o
 
 obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
 lib-$(CONFIG_MMU) += ioremap.o
@@ -26,7 +26,7 @@ obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
 	 bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
 	 gcd.o lcm.o list_sort.o uuid.o flex_array.o iovec.o clz_ctz.o \
 	 bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \
-	 percpu_ida.o
+	 percpu-refcount.o percpu_ida.o
 obj-y += string_helpers.o
 obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
 obj-y += kstrtox.o