When building for Atlas, Malta or SEAD convert the kernel to srecs by

default.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -731,6 +731,18 @@ ifdef CONFIG_BOOT_ELF64
 all:	$(vmlinux-64)
 endif
 
+ifdef CONFIG_MIPS_ATLAS
+all:	vmlinux.srec
+endif
+
+ifdef CONFIG_MIPS_MALTA
+all:	vmlinux.srec
+endif
+
+ifdef CONFIG_MIPS_SEAD
+all:	vmlinux.srec
+endif
+
 ifdef CONFIG_SNI_RM200_PCI
 all:	vmlinux.ecoff
 endif