ia64: fix build error with !COREDUMP

Fix linkage error when CONFIG_BINFMT_ELF is selected but CONFIG_COREDUMP
is not:

    ia64-linux-ld: arch/ia64/kernel/elfcore.o: in function `elf_core_write_extra_phdrs':
    elfcore.c:(.text+0x172): undefined reference to `dump_emit'
    ia64-linux-ld: arch/ia64/kernel/elfcore.o: in function `elf_core_write_extra_data':
    elfcore.c:(.text+0x2b2): undefined reference to `dump_emit'

Fixes: 1fcccba ("elf coredump: replace ELF_CORE_EXTRA_* macros by functions")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

arch/ia64/kernel/Makefile

@@ -40,7 +40,7 @@ obj-y				+= esi_stub.o	# must be in kernel proper
 endif
 obj-$(CONFIG_INTEL_IOMMU)	+= pci-dma.o
 
-obj-$(CONFIG_BINFMT_ELF)	+= elfcore.o
+obj-$(CONFIG_ELF_CORE)		+= elfcore.o
 
 # fp_emulate() expects f2-f5,f16-f31 to contain the user-level state.
 CFLAGS_traps.o  += -mfixed-range=f2-f5,f16-f31