linux: select proper defconfig on ARC 750d/770d

The Linux kernel "defconfig" on ARC is haps_hs_smp_defconfig, which
cannot be built on ARC 750d/770d targets, so let's use a kernel
defconfig that works properly on ARC 750d/770d.

Fixes:

  http://autobuild.buildroot.net/results/2913e5958cd6b20dbfdcdad304a5f5a0f8030d8d/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>
(cherry picked from commit 954b5514a92d9d8439d57a815f097046e6270bb9)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

linux/linux.mk

@@ -347,6 +347,8 @@ else ifeq ($(BR2_powerpc64),y)
 LINUX_KCONFIG_DEFCONFIG = ppc64_defconfig
 else ifeq ($(BR2_powerpc),y)
 LINUX_KCONFIG_DEFCONFIG = ppc_defconfig
+else ifeq ($(BR2_arc750d)$(BR2_arc770d),y)
+LINUX_KCONFIG_DEFCONFIG = axs101_defconfig
 else
 LINUX_KCONFIG_DEFCONFIG = defconfig
 endif