Revert "Unsignify lengths and addresses in chip functions and structs"

- probe_timing was changed to unsigned although we use negative values
  for special cases
- some code was not changed along hence did no longer compile:
  * dediprog's read and write functions
  * linux_spi's read and write functions
- it introduced a number of new sign conversion warnings
  (http://paste.flashrom.org/view.php?id=832)

To be safe this patch reverts all changes made in r1448, a corrected
patch will follow later.

Thanks to idwer for pointing out the problem first!

Corresponding to flashrom svn r1450.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
diff --git a/flashrom.c b/flashrom.c
index e2afd44..c565a43 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -564,7 +564,7 @@
 	flash->virtual_registers = (chipaddr)programmer_map_flash_region("flash chip registers", (0xFFFFFFFF - 0x400000 - size + 1), size);
 }
 
-int read_memmapped(struct flashchip *flash, uint8_t *buf, unsigned int start, int unsigned len)
+int read_memmapped(struct flashchip *flash, uint8_t *buf, int start, int len)
 {
 	chip_readn(buf, flash->virtual_memory + start, len);
 
@@ -710,7 +710,7 @@
  * @message	string to print in the "FAILED" message
  * @return	0 for success, -1 for failure
  */
-int verify_range(struct flashchip *flash, uint8_t *cmpbuf, unsigned int start, unsigned int len,
+int verify_range(struct flashchip *flash, uint8_t *cmpbuf, int start, int len,
 		 const char *message)
 {
 	int i;