serprog: Fix FWH/LPC by implementing serprog_map

The serprog protocol does only transmit 24 bit-wide address and ignores the
top 8 bit. This is fine as long as the underlying hardware ignores the latter
anyway (which is the case for parallel chips that even lack the respective pins).
FWH/LPC chips, however, operate on a full 32-bit (LPC) or 28-bit (FWH) address
space and would fail with the fallback mapping to NULL.

Corresponding to flashrom svn r1895.

Signed-off-by: Urja Rannikko <urjaman@gmail.com>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>

programmer.h

@@ -706,6 +706,7 @@ int register_master(const struct registered_master *mst);
 #if CONFIG_SERPROG == 1
 int serprog_init(void);
 void serprog_delay(unsigned int usecs);
+void *serprog_map(const char *descr, uintptr_t phys_addr, size_t len);
 #endif
 
 /* serial.c */