i2c: nuvoton: remove standard mode only

first version is only support standard mode.
remove this judgment to support standard/fast/fast plus  mode.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>

Changes for v2:
   - add commit message
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/i2c/npcm_i2c.c b/drivers/i2c/npcm_i2c.c
index ea4ef53..b867b6c 100644
--- a/drivers/i2c/npcm_i2c.c
+++ b/drivers/i2c/npcm_i2c.c
@@ -517,11 +517,6 @@
 	u32 sclfrq;
 	u8 hldt, val;
 
-	if (bus_freq > I2C_FREQ_100K) {
-		printf("Support standard mode only\n");
-		return -EINVAL;
-	}
-
 	/* SCLFRQ = T(SCL)/4/T(CLK) = FREQ(CLK)/4/FREQ(SCL) */
 	sclfrq = freq / (bus_freq * 4);
 	if (sclfrq < SCLFRQ_MIN || sclfrq > SCLFRQ_MAX)