w1: add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support

Add support for the Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC.

It was suggested to combine this functionality with the current ds2782
driver.  Unfortunately, I'm unable to commit the time to refactoring this
driver to that extent and I don't have a platform with the ds2782 part to
validate that there are no regression issues by adding this functionality.

[akpm@linux-foundation.org: use min_t()]
Signed-off-by: Clifton Barnes <cabarnes@indesign-llc.com>
Tested-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
index 7513759..97479ae 100644
--- a/drivers/w1/w1_family.h
+++ b/drivers/w1/w1_family.h
@@ -37,6 +37,7 @@
 #define W1_FAMILY_DS2408	0x29
 #define W1_EEPROM_DS2431	0x2D
 #define W1_FAMILY_DS2760	0x30
+#define W1_FAMILY_DS2780	0x32
 
 #define MAXNAMELEN		32