XArray: Export __xa_foo to non-GPL modules

Without this, it's not possible to use static inlines like xa_store_bh()
and xa_erase_irq().

Signed-off-by: Matthew Wilcox <[e-mail]>

lib/xarray.c

···
 	XA_STATE(xas, xa, index);
 	return xas_result(&xas, xas_store(&xas, NULL));
 }
-EXPORT_SYMBOL_GPL(__xa_erase);
+EXPORT_SYMBOL(__xa_erase);
 
 /**
  * xa_store() - Store this entry in the XArray.
···
 	if (entry)
 		xas_set_mark(&xas, mark);
 }
-EXPORT_SYMBOL_GPL(__xa_set_mark);
+EXPORT_SYMBOL(__xa_set_mark);
 
 /**
  * __xa_clear_mark() - Clear this mark on this entry while locked.
···
 	if (entry)
 		xas_clear_mark(&xas, mark);
 }
-EXPORT_SYMBOL_GPL(__xa_clear_mark);
+EXPORT_SYMBOL(__xa_clear_mark);
 
 /**
  * xa_get_mark() - Inquire whether this mark is set on this entry.