clk: stm32mp1: fix bit width of hse_rtc divider

Fix the bit width of the hse rtc divider because it's off by one.

Fixes: 2c87c9d33117 ("clk: stm32mp1: add RTC clock")
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
diff --git a/drivers/clk/clk-stm32mp1.c b/drivers/clk/clk-stm32mp1.c
index ca98763..a0ae8dc 100644
--- a/drivers/clk/clk-stm32mp1.c
+++ b/drivers/clk/clk-stm32mp1.c
@@ -1962,7 +1962,7 @@
 		  _DIV(RCC_ETHCKSELR, 4, 4, 0, NULL)),
 
 	/* RTC clock */
-	DIV(NO_ID, "ck_hse_rtc", "ck_hse", 0, RCC_RTCDIVR, 0, 7, 0),
+	DIV(NO_ID, "ck_hse_rtc", "ck_hse", 0, RCC_RTCDIVR, 0, 6, 0),
 
 	COMPOSITE(RTC, "ck_rtc", rtc_src, CLK_OPS_PARENT_ENABLE |
 		   CLK_SET_RATE_PARENT,