ARM: vfp: Add vfp_disable for problematic platforms

Some platforms might not be able to fully utilize VFP when e.g: one CPU
out of two in a SMP complex lacks a VFP unit. Adding code to migrate
task to the CPU which has a VFP unit would be cumbersome and not
performant, instead, just add the ability to disable VFP.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/include/asm/vfp.h

@@ -91,4 +91,8 @@
 #define VFPOPDESC_UNUSED_MASK	(0xFF << VFPOPDESC_UNUSED_BIT)
 #define VFPOPDESC_OPDESC_MASK	(~(VFPOPDESC_LENGTH_MASK | VFPOPDESC_UNUSED_MASK))
 
+#ifndef __ASSEMBLY__
+void vfp_disable(void);
+#endif
+
 #endif /* __ASM_VFP_H */