[U-Boot] [PATCH v4 4/6] armv7: Use -march=armv7-a and thereby enable Thumb-2

[Aneesh V <aneesh@ti.com>]

Enable -march=armv7-a for armv7 platforms if the tool-chain
supports it. This in turn results in Thumb-2 code generated
for these platforms if CONFIG_SYS_THUMB_BUILD is enabled.

Signed-off-by: Aneesh V <aneesh@ti.com>
---
I believe armv7-a is fine for all the SoCs except Tegra2
and I see that Tegra2 is already making the necessary
exception in .../armv7/tegra2/config.mk

Let me know if any other SoC has a problem with armv7-a

Changes in V4:
- Replaced "+=" with ":=" for make variable that involves
  computation

Changes in V3:
- None

Changes from V1 to V2:
- None

Changes from RFC to V1:
- Enabled armv7-a from armv7/config.mk instead of from
  omap config.mk files
---
 arch/arm/cpu/armv7/config.mk |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm/cpu/armv7/config.mk b/arch/arm/cpu/armv7/config.mk
index 83ddf10..6d4b13c 100644
--- a/arch/arm/cpu/armv7/config.mk
+++ b/arch/arm/cpu/armv7/config.mk
@@ -22,8 +22,11 @@
 #
 PLATFORM_RELFLAGS += -fno-common -ffixed-r8 -msoft-float
 
-# Make ARMv5 to allow more compilers to work, even though its v7a.
-PLATFORM_CPPFLAGS += -march=armv5
+# If armv7-a is not supported by GCC fall-back to armv5, which is
+# supported by more tool-chains
+PF_CPPFLAGS_ARMV7 := $(call cc-option, -march=armv7-a, -march=armv5)
+PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARMV7)
+
 # =========================================================================
 #
 # Supply options according to compiler version
-- 
1.7.1