[bsp][n32] fix USART2 remap macro

[Old-Ding]

Summary

• fix the USART2 remap-2 macro used by the N32G452 mini-system BSP
• keep the UART2 pin remap flow unchanged

Root cause

The BSP selected GPIO_RMCP2_USART2, but the N32 standard peripheral headers define the remap macro as GPIO_RMP2_USART2. Enabling BSP_USING_UART2_PIN_RMP2 therefore references an undefined macro during compilation.

Closes #9013

Testing

• git diff --check
• verified the diff is limited to one macro replacement in bsp/n32g452xx/n32g452xx-mini-system/board/msp/n32_msp.c
• verified GPIO_RMP2_USART2 is defined in bsp/n32g452xx/Libraries/N32_Std_Driver/n32g45x_std_periph_driver/inc/n32g45x_gpio.h
• verified GPIO_RMCP2_USART2 no longer appears under bsp/n32g452xx
• verified the touched file keeps CRLF line endings

Not run: N32G452 BSP build. This machine does not have scons, gcc, arm-none-eabi-gcc, or clang installed.

[github-actions]

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