drivers: clock_control: sf32lb: fix clock selcection error

Fix clock selction error

Signed-off-by: Qingsong Gou <gouqs@hotmail.com>

Author: ck-telecom

drivers/clock_control/clock_control_sf32lb_rcc.c

@@ -144,12 +144,10 @@ static int clock_control_sf32lb_rcc_init(const struct device *dev)
 		(void)clock_control_on(config->hxt48, NULL);
 
 		/* TODO: make this configurable */
-		val = sys_read32(config->base + HPSYS_RCC_CFGR);
-		val &= HPSYS_RCC_CSR_SEL_SYS_Msk;
+		val = sys_read32(config->base + HPSYS_RCC_CSR);
+		val &= ~HPSYS_RCC_CSR_SEL_SYS_Msk;
 		val |= HPSYS_RCC_CSR_SEL_SYS_CLK_HXT48;
-		sys_write32(val, config->base + HPSYS_RCC_CSR);
 
-		val = sys_read32(config->base + HPSYS_RCC_CSR);
 		val &= ~HPSYS_RCC_CSR_SEL_PERI_Msk;
 		val |= HPSYS_RCC_CSR_SEL_PERI_CLK_HXT48;
 		sys_write32(val, config->base + HPSYS_RCC_CSR);