linux: arc: disable kernel unwinding to fix modules loading

With update of binutils for ARC (this is now based on upstream 2.26)
we noticed issues with loadable kernel modules.

Something like that was happening:
--------------------->8-------------------
mbcache: unknown relocation: 49
insmod: can't insert './mbcache.ko': invalid module format
--------------------->8-------------------

More details could be found in that discussion in binutils mailing list:
http://thread.gmane.org/gmane.comp.gnu.binutils/74662

As of now the simplest work-around is to disable in-kernel unwinder
for now. That will at least allow us to use modules again.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: John Crispin <john@phrozen.org>

target/linux/arc770/config-4.4

@@ -18,7 +18,7 @@ CONFIG_ARC_CURR_IN_REG=y
 CONFIG_ARC_DBG=y
 # CONFIG_ARC_DBG_TLB_MISS_COUNT is not set
 # CONFIG_ARC_DBG_TLB_PARANOIA is not set
-CONFIG_ARC_DW2_UNWIND=y
+# CONFIG_ARC_DW2_UNWIND is not set
 CONFIG_ARC_EMUL_UNALIGNED=y
 # CONFIG_ARC_FPU_SAVE_RESTORE is not set
 CONFIG_ARC_HAS_DCACHE=y
@@ -78,7 +78,6 @@ CONFIG_HAVE_FUTEX_CMPXCHG=y
 CONFIG_HAVE_IOREMAP_PROT=y
 CONFIG_HAVE_LATENCYTOP_SUPPORT=y
 CONFIG_HAVE_MEMBLOCK=y
-CONFIG_HAVE_MOD_ARCH_SPECIFIC=y
 CONFIG_HAVE_NET_DSA=y
 CONFIG_HAVE_OPROFILE=y
 CONFIG_HAVE_PERF_EVENTS=y

target/linux/archs38/config-4.4

@@ -15,7 +15,7 @@ CONFIG_ARC_CURR_IN_REG=y
 CONFIG_ARC_DBG=y
 # CONFIG_ARC_DBG_TLB_MISS_COUNT is not set
 # CONFIG_ARC_DBG_TLB_PARANOIA is not set
-CONFIG_ARC_DW2_UNWIND=y
+# CONFIG_ARC_DW2_UNWIND is not set
 CONFIG_ARC_HAS_COH_CACHES=y
 CONFIG_ARC_HAS_DCACHE=y
 # CONFIG_ARC_HAS_DCCM is not set
@@ -85,7 +85,6 @@ CONFIG_HAVE_FUTEX_CMPXCHG=y
 CONFIG_HAVE_IOREMAP_PROT=y
 CONFIG_HAVE_LATENCYTOP_SUPPORT=y
 CONFIG_HAVE_MEMBLOCK=y
-CONFIG_HAVE_MOD_ARCH_SPECIFIC=y
 CONFIG_HAVE_NET_DSA=y
 CONFIG_HAVE_OPROFILE=y
 CONFIG_HAVE_PERF_EVENTS=y
@@ -175,7 +174,6 @@ CONFIG_SRCU=y
 CONFIG_STACKTRACE=y
 CONFIG_STMMAC_ETH=y
 CONFIG_STMMAC_PLATFORM=y
-# CONFIG_SUNXI_SRAM is not set
 CONFIG_TICK_CPU_ACCOUNTING=y
 CONFIG_UNINLINE_SPIN_UNLOCK=y
 CONFIG_USB_SUPPORT=y