Fix prvalue to xvalue conversion address space assignment

The common address deduction rules assumed prvalue-to-xvalue conversion
can only happens inside a function.
The patch aligns the rules to match declaration rules.

adoc/chapters/device_compiler.adoc

@@ -725,7 +725,7 @@ The variable declarations get assigned to an address space depending on their
 scope and storage class:
 
   * Namespace scope
-  ** If the type is [code]#const#, the address space the declaration is assigned to
+  ** If the type is [code]#const#, the address space of the declaration is assigned to
      is implementation-defined. If the target of the SYCL backend can represent the
      generic address space, then the assigned address space must be compatible with
      the generic address space.
@@ -748,9 +748,11 @@ code called by the device kernel.
   ** Static data members are treated the same way as for variable in
      namespace scope
 
-The result of a prvalue-to-xvalue conversion is assigned to the local
-address space if it happens in a hierarchical context or to the private
-address space otherwise.
+If a prvalue-to-xvalue conversion happens in a block scope or function parameter scope,
+the result is assigned to the local address space if it happens a hierarchical context
+otherwise it is assigned to the private address space.
+It the prvalue-to-xvalue conversion happens in another scope, the result is assigned
+in the same way as declaration in namespace scope.
 
 
 [[subsec:genericAddressSpace]]