mlx5: Remove call to ida_pre_get

The mlx5 driver calls ida_pre_get() in a loop for no readily apparent
reason.  The driver uses ida_simple_get() which will call ida_pre_get()
by itself and there's no need to use ida_pre_get() unless using
ida_get_new().

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>