net: zynq: Allocate BD_SPACE in connection to RX_BUF

BD_SEPRN_SPACE should not have hard coded value and it will be
calculated based on the number of buffer descriptors that we
would like to use.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/zynq_gem.c

@@ -145,7 +145,7 @@ struct emac_bd {
  */
 #define BD_SPACE	0x100000
 /* BD separation space */
-#define BD_SEPRN_SPACE	64
+#define BD_SEPRN_SPACE	(RX_BUF * sizeof(struct emac_bd))
 
 /* Initialized, rxbd_current, rx_first_buf must be 0 after init */
 struct zynq_gem_priv {