common: Move jumptable_init() out of common.h

This function is defined in exports.c so move it to its header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/include/exports.h b/include/exports.h
index 35f4632..cbd16fc 100644
--- a/include/exports.h
+++ b/include/exports.h
@@ -13,6 +13,9 @@
 
 struct spi_slave;
 
+/* Set up the jump table for use by the API */
+void jumptable_init(void);
+
 /* These are declarations of exported functions available in C code */
 unsigned long get_version(void);
 int  getc(void);