mtd: cfi: introduce CFI_FLASH_BANKS

Replace CONFIG_SYS_MAX_FLASH_BANKS by CFI_FLASH_BANKS to prepare
Kconfig migration and avoid to redefine CONFIG_SYS_MAX_FLASH_BANKS
in cfi_flash.h.

After this patch CONFIG_SYS_MAX_FLASH_BANKS should be never used in
the cfi code: use CFI_MAX_FLASH_BANKS for struct size or CFI_FLASH_BANKS
for number of CFI banks which can be dynamic.

This patch modify all the files which include mtd/cfi_flash.h.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/common/update.c b/common/update.c
index f5c8684..b9ad475 100644
--- a/common/update.c
+++ b/common/update.c
@@ -112,12 +112,12 @@
 
 	if (prot == 0) {
 		saved_prot_info =
-			calloc(CONFIG_SYS_MAX_FLASH_BANKS * CONFIG_SYS_MAX_FLASH_SECT, 1);
+			calloc(CFI_FLASH_BANKS * CONFIG_SYS_MAX_FLASH_SECT, 1);
 		if (!saved_prot_info)
 			return 1;
 	}
 
-	for (bank = 0; bank < CONFIG_SYS_MAX_FLASH_BANKS; ++bank) {
+	for (bank = 0; bank < CFI_FLASH_BANKS; ++bank) {
 		cnt = 0;
 		info = &flash_info[bank];