ARC: rework setting of ARC CPU specific compiler options

It's a very rare if at all existing occasion when ARC CPU template
is used as is w/o any changes - in the end it's a beauty and competitive
advantage of ARC cores to be tailored for a particular use-case - and
so it doesn't make a lot of sense to offer template-based "-mcpu" selection.
Given for each and every platform we end-up adding quite a few more flags
it's logical to move "-mcpu" selection to platform's definition as well
which we exactly do here.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/board/synopsys/hsdk/config.mk b/board/synopsys/hsdk/config.mk
index 9e280f9..5ae22fa 100644
--- a/board/synopsys/hsdk/config.mk
+++ b/board/synopsys/hsdk/config.mk
@@ -2,6 +2,10 @@
 #
 # Copyright (C) 2018 Synopsys, Inc. All rights reserved.
 
+PLATFORM_CPPFLAGS += -mcpu=hs38_linux -mlittle-endian -matomic -mll64 \
+                     -mdiv-rem -mswap -mnorm -mmpy-option=9 -mbarrel-shifter \
+                     -mfpu=fpud_all
+
 bsp-generate: u-boot u-boot.bin
 	$(Q)python3 $(srctree)/board/$(BOARDDIR)/headerize-hsdk.py \
 		--arc-id 0x52 --image $(srctree)/u-boot.bin \