setupapi: Constify a variable

[Andrew Talbot]

Changelog:
    setupapi: Constify a variable.

diff --git a/dlls/setupapi/devinst.c b/dlls/setupapi/devinst.c
index 7613814..af4f4d3 100644
--- a/dlls/setupapi/devinst.c
+++ b/dlls/setupapi/devinst.c
@@ -3052,7 +3052,7 @@ struct PropertyMapEntry
     LPCWSTR nameW;
 };
 
-static struct PropertyMapEntry PropertyMap[] = {
+static const struct PropertyMapEntry PropertyMap[] = {
     { REG_SZ, "DeviceDesc", DeviceDesc },
     { REG_MULTI_SZ, "HardwareId", HardwareId },
     { REG_MULTI_SZ, "CompatibleIDs", CompatibleIDs },