tools/libxl: fix setting altp2m param broken by 1e9bc407cf

The patch 1e9bc407cf mistakenly converted the altp2m config option to a
boolean. This is incorrect and breaks external-only usecases of altp2m that
is set with a value of 2.

Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/libxl/libxl_x86.c

@@ -391,7 +391,7 @@ static int hvm_set_conf_params(libxl__gc *gc, uint32_t domid,
     libxl_ctx *ctx = libxl__gc_owner(gc);
     xc_interface *xch = ctx->xch;
     int ret = ERROR_FAIL;
-    bool altp2m = info->altp2m;
+    unsigned int altp2m = info->altp2m;
 
     switch(info->type) {
     case LIBXL_DOMAIN_TYPE_HVM: