flash/nor/sfdp: expose SFDP_MAGIC in sfdp.h

Could be handy for dummy transfer size detection.

Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Change-Id: Ibb485218f6c2ff9066910bb58be0fc614b77add3
Reviewed-on: https://review.openocd.org/c/openocd/+/8438
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins
Reviewed-by: Andreas Bolsch <hyphen0break@gmail.com>

src/flash/nor/sfdp.c

@@ -12,7 +12,6 @@
 #include "spi.h"
 #include "sfdp.h"
 
-#define SFDP_MAGIC			0x50444653
 #define SFDP_ACCESS_PROT	0xFF
 #define SFDP_BASIC_FLASH	0xFF00
 #define SFDP_4BYTE_ADDR		0xFF84

src/flash/nor/sfdp.h

@@ -7,6 +7,8 @@
 #ifndef OPENOCD_FLASH_NOR_SFDP_H
 #define OPENOCD_FLASH_NOR_SFDP_H
 
+#define SFDP_MAGIC          0x50444653
+
 /* per JESD216D 'addr' is *byte* based but must be word aligned,
  * 'buffer' is word based, word aligned and always little-endian encoded,
  * in the flash, 'addr_len' is 3 or 4, 'dummy' ***usually*** 8