flash/nor: move variable's declaration in C file

Variables should not be declared in the include file, otherwise
multiple include will cause multiple instances.

Move the declaration in the C file and make it static.

Change-Id: I8b4884cba643a792a78df4e123aa324b19d92279
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7172
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins

src/flash/nor/cc3220sf.c

@@ -22,6 +22,11 @@ struct cc3220sf_bank {
 	struct armv7m_algorithm armv7m_info;
 };
 
+/* Flash helper algorithm for CC3220SF */
+static const uint8_t cc3220sf_algo[] = {
+#include "../../../contrib/loaders/flash/cc3220sf/cc3220sf.inc"
+};
+
 static int cc3220sf_mass_erase(struct flash_bank *bank)
 {
 	struct target *target = bank->target;