Blackfin arch: fix bug NOR Flash MTD mount fail

Config EBIU flash mode properly. EBIU_MODE EBIU_FCTL
EBIU_MBSCTL register should be configurd to Flash
mode.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 2e5ce84..3bb25da 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -866,6 +866,20 @@
 	default 0x99B3
 endmenu
 
+config EBIU_MBSCTLVAL
+	hex "EBIU Bank Select Control Register"
+	depends on BF54x
+	default 0
+
+config EBIU_MODEVAL
+	hex "Flash Memory Mode Control Register"
+	depends on BF54x
+	default 1
+
+config EBIU_FCTLVAL
+	hex "Flash Memory Bank Control Register"
+	depends on BF54x
+	default 6
 endmenu
 
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