configure: fix ARM VFPv2

The gcc -mfpu flag for VFPv2 is 'vfp', not 'vfpv2'.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

diff -durN a/configure b/configure
--- a/configure
+++ b/configure
@@ -611,7 +611,7 @@
     o['variables']['arm_fpu'] = 'vfpv3'
     o['variables']['arm_version'] = '7'
   else:
-    o['variables']['arm_fpu'] = 'vfpv2'
+    o['variables']['arm_fpu'] = 'vfp'
     o['variables']['arm_version'] = '6' if is_arch_armv6() else 'default'
 
   o['variables']['arm_thumb'] = 0      # -marm