imx8qm-mek: Fix early print

Function `arm64_lowputc` corrupted the x1 register which is used in function `boot_stage_puts`.

Signed-off-by: ouyangxiangzhen <ouyangxiangzhen@xiaomi.com>

arch/arm64/src/imx8/imx8qm_lowputc.S

@@ -84,6 +84,6 @@ SECTION_FUNC(text, arm64_earlyprintinit)
 GTEXT(arm64_lowputc)
 SECTION_FUNC(text, arm64_lowputc)
     ldr   x15, =UART1_BASE_ADDRESS
-    early_uart_ready x15, 1
+    early_uart_ready x15, 2
     early_uart_transmit x15, w0
     ret