Fixes SPI access for ESP32C6

[outlandnish]

Updates the pre-processor check to also support the SPI peripheral on the ESP32C6

[rabadalCactus]

I understand that maybe you want to do this in another PR, but this is not enough to adapt the library for esp32c6.
You need to adapt the clock source for the RMT too
RmtDriver5.cpp line 125

        .clk_src = RMT_CLK_SRC_APB,

I suggest using default, which is APB for both S3 and C3. Default on C6 is SOC_MOD_CLK_PLL_F80M.

        .clk_src = RMT_CLK_SRC_DEFAULT,

I validated this with the sample code on the ESP32-c6DevKitC-1

[outlandnish]

Ah yeah, good call!