kbuild: Convert missed L_TARGET references

When converting all L_TARGETs to lib.a, I missed these instances.

arch/ppc/boot/openfirmware/Makefile

@@ -21,7 +21,7 @@ CHRPOBJS = ../common/crt0.o $(COMMONOBJS) chrpmain.o
 NEWWORLDOBJS = ../common/crt0.o $(COMMONOBJS) newworldmain.o
 
 EXTRA_TARGETS	:= $(COFFOBJS) $(CHRPOBJS) $(NEWWORLDOBJS)
-LIBS = $(TOPDIR)/lib/lib.a ../lib/zlib.a ../of1275/of1275.a
+LIBS = $(TOPDIR)/lib/lib.a ../lib/lib.a ../of1275/of1275.a
 
 ADDNOTE := ../utils/addnote
 MKNOTE := ../utils/mknote

arch/ppc/boot/prep/Makefile

@@ -24,7 +24,7 @@ boot-y				:= head.o ../simple/legacy.o misc.o \
 					../common/misc-common.o \
 					../common/mpc10x_memory.o
 OBJCOPY_ARGS			= -O elf32-powerpc
-LIBS 				= ../lib/zlib.a
+LIBS 				= ../lib/lib.a
 
 boot-$(CONFIG_SERIAL_8250_CONSOLE) += ../common/ns16550.o
 boot-$(CONFIG_VGA_CONSOLE)	+= vreset.o kbd.o

arch/ppc/boot/simple/Makefile

@@ -152,7 +152,7 @@ endif
 boot-$(CONFIG_SERIAL_8250_CONSOLE) += ../common/ns16550.o
 
 EXTRA_TARGETS			:= $(boot-y)
-LIBS				:= ../lib/zlib.a
+LIBS				:= ../lib/lib.a
 
 # Tools
 MKBUGBOOT			:= ../utils/mkbugboot