i2c: nuvoton: renamed the NPCM i2c driver

The Makefile name is npcm_i2c but the driver is npcm-i2c.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
Reviewed-by: Heiko Schocher <hs@denx.de>

diff --git a/drivers/i2c/npcm-i2c.c b/drivers/i2c/npcm_i2c.c
similarity index 100%
rename from drivers/i2c/npcm-i2c.c
rename to drivers/i2c/npcm_i2c.c