rkcommon.c: Remove unused rkcommon_spi_to_offset

This function is unused, remove.  Reported by clang-3.8.

Fixes: a1c29d4b43 ("rockchip: mkimage: set init_boot_size to avoid ...")
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

tools/rkcommon.c

@@ -226,11 +226,6 @@ static inline unsigned rkcommon_offset_to_spi(unsigned offset)
 	return ((offset & ~0x7ff) << 1) + (offset & 0x7ff);
 }
 
-static inline unsigned rkcommon_spi_to_offset(unsigned offset)
-{
-	return ((offset & ~0x7ff) >> 1) + (offset & 0x7ff);
-}
-
 static int rkcommon_parse_header(const void *buf, struct header0_info *header0,
 				 struct spl_info **spl_info)
 {