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/dummyflasher.c b/dummyflasher.c
index 84650e7..be8f552 100644
--- a/dummyflasher.c
+++ b/dummyflasher.c
@@ -63,7 +63,7 @@
 static int dummy_spi_send_command(unsigned int writecnt, unsigned int readcnt,
 		      const unsigned char *writearr, unsigned char *readarr);
 static int dummy_spi_write_256(struct flashchip *flash, uint8_t *buf,
-			       unsigned int start, unsigned int len);
+			       int start, int len);
 
 static const struct spi_programmer spi_programmer_dummyflasher = {
 	.type		= SPI_CONTROLLER_DUMMY,
@@ -528,7 +528,7 @@
 }
 
 static int dummy_spi_write_256(struct flashchip *flash, uint8_t *buf,
-			       unsigned int start, unsigned int len)
+			       int start, int len)
 {
 	return spi_write_chunked(flash, buf, start, len,
 				 spi_write_256_chunksize);