soc: nxp: rw: Update system core clock frequency

After updating the main_clk, need to update the frequency tracked in
HAL MCUXpresso SDK framework for other drivers.

Signed-off-by: Derek Snell <derek.snell@nxp.com>
(cherry picked from commit 793e44a)

soc/nxp/rw/soc.c

@@ -132,6 +132,8 @@ __ramfunc void clock_init(void)
 	CLOCK_SetClkDiv(kCLOCK_DivSystickClk, 1U);
 	CLOCK_AttachClk(kSYSTICK_DIV_to_SYSTICK_CLK);
 
+	SystemCoreClockUpdate();
+
 	/* Set PLL FRG clock to 20MHz. */
 	CLOCK_SetClkDiv(kCLOCK_DivPllFrgClk, 13U);