soc/mediatek/mt8186: Correct SPI_HZ for PLL

The SPI speed is 218.4MHz, so correct the value of SPI_HZ.

BUG=b:202871018
TEST=build pass

Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Change-Id: I6e8ba10a851e1507405cdd41939a176462734487
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59939
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

src/soc/mediatek/mt8186/include/soc/pll.h

@@ -492,12 +492,12 @@ enum {
 /* top_div rate */
 enum {
 	CLK26M_HZ	= 26 * MHz,
-	UNIVPLL_D6_D2_HZ = UNIV2PLL_HZ / 2 / 6 / 2,
+	MAINPLL_D5_HZ = MAINPLL_HZ / 5,
 };
 
 /* top_mux rate */
 enum {
-	SPI_HZ		= UNIVPLL_D6_D2_HZ,
+	SPI_HZ		= MAINPLL_D5_HZ,
 	UART_HZ		= CLK26M_HZ,
 };