drm/i915: Move PTE_READ_ONLY to ->pte_encode vfunc

It's only used as a flag there, so unconfuse things a bit.
Also separate the bind_vma flag space from the pte_encode flag
space in the code.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 12d0ded..fb0a04a 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -158,7 +158,6 @@
 	/** Flags and address space this VMA is bound to */
 #define GLOBAL_BIND	(1<<0)
 #define LOCAL_BIND	(1<<1)
-#define PTE_READ_ONLY	(1<<2)
 	unsigned int bound : 4;
 
 	/**
@@ -261,6 +260,8 @@
 	gen6_pte_t (*pte_encode)(dma_addr_t addr,
 				 enum i915_cache_level level,
 				 bool valid, u32 flags); /* Create a valid PTE */
+	/* flags for pte_encode */
+#define PTE_READ_ONLY	(1<<0)
 	int (*allocate_va_range)(struct i915_address_space *vm,
 				 uint64_t start,
 				 uint64_t length);