ramips: mtk-mmc: mt76x8: check ESD_MODE before applying AGPIO_CFG

ramips: mtk-mmc: mt76x8: check ESD_MODE before applying AGPIO_CFG

Since mt76x8an ver1 eco2, SDXC pins can be switched to the
following pinmap:
sd_d1  -> PAD_I2S_SDI
sd_d0  -> PAD_I2S_WS
sd_cmd -> PAD_I2S_CLK
sd_d3  -> PAD_I2C_SCLK
sd_d2  -> PAD_I2C_SD
sd_clk -> PAD_GPIO0
sd_wp  -> PAD_TXD1
sd_cd  -> PAD_RXD1

To use this pinmap, one would need to set ESD_MODE bit (bit 15)
to 1 in GPIO1_MODE and switch other used pads into GPIO mode.
In this mode, we don't need to switch ethernet pins to digital
pad.

Check ESD_MODE bit before applying AGPIO_CFG and use rt_sysc_m32
to set it.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>