zynq-common: Enable ISSI SPI-NOR flash support

This patch enabled CONFIG_SPI_FLASH_ISSI for qspi on zynq boards.

Signed-off-by: Jagan Teki <jteki@openedev.com>
Cc: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Cc: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/configs/zynq-common.h b/include/configs/zynq-common.h
index cac76d2..acb8670 100644
--- a/include/configs/zynq-common.h
+++ b/include/configs/zynq-common.h
@@ -75,6 +75,7 @@
 /* QSPI */
 #ifdef CONFIG_ZYNQ_QSPI
 # define CONFIG_SF_DEFAULT_SPEED	30000000
+# define CONFIG_SPI_FLASH_ISSI
 # define CONFIG_SPI_FLASH_SPANSION
 # define CONFIG_SPI_FLASH_STMICRO
 # define CONFIG_SPI_FLASH_WINBOND