Fix auto LCD serial port for MKS Monster8 V1

[narno2202]

Description

Wiring a MKS-H43 screen on Monster8 V1 USART1 port doesn't work because the default serial port isn't the good one: set to 3 instead of 1. The value can't be overridden in Configuration.h by configuring another serial port. Adding MKS_MONSTER8_V1 in Conditionals_adv.h "#if LCD_IS_SERIAL_HOST..."

#if MB(MKS_MONSTER8_V1, BTT_SKR_MINI_E3_V1_0, BTT_SKR_MINI_E3_V1_2, BTT_SKR_MINI_E3_V2_0, BTT_SKR_MINI_E3_V3_0, BTT_SKR_MINI_E3_V3_0_1, BTT_SKR_E3_TURBO, BTT_OCTOPUS_V1_1, AQUILA_V101)
    #define LCD_SERIAL_PORT 1

solve the issue.

Requirements

MKS_MONTER8 V1
MKS_H43 screen (or probably anther DGUS style screen) wired solely on USART 1

Benefits

Screen works as needed

Configurations

Related Issues

[sjasonsmith]

@thisiskeithb it looks like you added this board, does this change seem correct?

I trust that @narno2202's change fixes their use case, but don't know if that is potentially breaking scenarios using other serial ports with different configs.

[thisiskeithb]

does this change seem correct?

I have no way to test it since my H43 screen has never worked.

narno2202 has the hardware in hand/submitted this PR, so I assume it works.

[sjasonsmith]

I see this on the MKS GitHub page, so it looks like 1 is correct for their intended use-cases:

USART(usart1:PA9,PA10) support [MKS H43](https://www.aliexpress.com/item/1005002008179262.html) or for other serial communication