acpi: has_immutable_rsdp->!rsdp_in_ram

As comment in acpi-build.c notes, RSDP is not really immutable.  So it's
really a question of whether it's in RAM, name the variable accordingly.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>


diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 85cc86a..3b99966 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -104,7 +104,7 @@
     int legacy_acpi_table_size;
     bool has_acpi_build;
     bool has_reserved_memory;
-    bool has_immutable_rsdp;
+    bool rsdp_in_ram;
 };
 
 /* parallel.c */