spi: sam0: Add support for SAME54

[benpicco]

The SPI SERCOM peripheral found on the SAMD5x/SAME5x is very much alike
the one found in previous SAM0 MCUs.

Only the clock setup is different.

split off from #14685

[zephyrbot]

All checks passed.

checkpatch (informational only, not a failure)

-:68: WARNING:LONG_LINE: line over 80 characters
#68: FILE: drivers/spi/spi_sam0.c:783:
+#define SPI_SAM0_DEFINE_CONFIG(n)						\

-:69: WARNING:LONG_LINE: line over 80 characters
#69: FILE: drivers/spi/spi_sam0.c:784:
+	static const struct spi_sam0_config spi_sam0_config_##n = {		\

-:70: WARNING:LONG_LINE: line over 80 characters
#70: FILE: drivers/spi/spi_sam0.c:785:
+		.regs = (SercomSpi *)DT_ATMEL_SAM0_SPI_SERCOM_##n##_BASE_ADDRESS,\

-:71: WARNING:LONG_LINE: line over 80 characters
#71: FILE: drivers/spi/spi_sam0.c:786:
+		.mclk = MCLK_SERCOM##n,						\

-:72: WARNING:LONG_LINE: line over 80 characters
#72: FILE: drivers/spi/spi_sam0.c:787:
+		.mclk_mask = MCLK_SERCOM##n##_MASK,				\

-:73: WARNING:LONG_LINE: line over 80 characters
#73: FILE: drivers/spi/spi_sam0.c:788:
+		.gclk_core_id = SERCOM##n##_GCLK_ID_CORE,			\

-:74: WARNING:LONG_LINE: line over 80 characters
#74: FILE: drivers/spi/spi_sam0.c:789:
+		.pads = SPI_SAM0_SERCOM_PADS(n)					\

- total: 0 errors, 7 warnings, 91 lines checked

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Your patch has style problems, please review.

NOTE: Ignored message types: AVOID_EXTERNS BRACES CONFIG_EXPERIMENTAL CONST_STRUCT DATE_TIME FILE_PATH_CHANGES MINMAX NETWORKING_BLOCK_COMMENT_STYLE PRINTK_WITHOUT_KERN_LEVEL SPLIT_STRING VOLATILE

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      them to the maintainers.

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