configs: Move CONFIG_SPI_FLASH into defconfigs

Completely move CONFIG_SPI_FLASH from remaining board header files to
defconfigs

Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> #zynq-microzed
diff --git a/configs/popmetal-rk3288_defconfig b/configs/popmetal-rk3288_defconfig
index 5cbcb89..ca194fd 100644
--- a/configs/popmetal-rk3288_defconfig
+++ b/configs/popmetal-rk3288_defconfig
@@ -51,6 +51,7 @@
 CONFIG_SYS_I2C_ROCKCHIP=y
 CONFIG_MMC_DW=y
 CONFIG_MMC_DW_ROCKCHIP=y
+CONFIG_SPI_FLASH=y
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_GMAC_ROCKCHIP=y