parisc: move core-y in arch/parisc/Makefile to arch/parisc/Kbuild

Use obj-y to clean up Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/Kbuild

 # SPDX-License-Identifier: GPL-2.0-only
+obj-y	+= mm/ kernel/ math-emu/

arch/parisc/Makefile

@@ -111,9 +111,6 @@ KBUILD_CFLAGS	+= $(cflags-y)
 LIBGCC		:= $(shell $(CC) -print-libgcc-file-name)
 export LIBGCC
 
-kernel-y			:= mm/ kernel/ math-emu/
-
-core-y	+= $(addprefix arch/parisc/, $(kernel-y))
 libs-y	+= arch/parisc/lib/ $(LIBGCC)
 
 boot	:= arch/parisc/boot