add external spi-nor flash will build fail

[lgl88911]

Describe the bug
I add spi-nor flash for nrf52832 board, want to the external spi flash & nrf52832 internal flash work same times. but build error:

zephyr/drivers/flash/spi_nor.c:388:47: error: 'DT_JEDEC_SPI_NOR_0_ERASE_BLOCK_SIZE' undeclared here (not in a function)
zephyr/drivers/flash/spi_nor.c:409:22: error: 'DT_JEDEC_SPI_NOR_0_WRITE_BLOCK_SIZE' undeclared here (not in a function);

To Reproduce
Steps to reproduce the behavior:

1. modify my board dts, add spi-nor flash tree:

&spi2 {
	status = "ok";
	sck-pin = <4>;
	mosi-pin = <5>;
	miso-pin = <13>;

	cs-gpios = <&gpio0 15 0>;

	w25x16vsi0: w25x16vsi@0 {
		compatible = "jedec,spi-nor";
		reg = <0>;
		spi-max-frequency = <2000000>;
		label = "W25X16VSI";
		jedec-id = <0xEF 0x80 0x3a>;
		size = <0x1000000>;
		erase-block-size = <0x10000>;
		write-block-size = <1>;
		hold-gpios = <&gpio0 9 0>;
	};
};

2. modify my board default conf，add spi-nor flash config

CONFIG_SPI_2=y
CONFIG_SPI_2_NRF_SPI=y
CONFIG_FLASH=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_CS_WAIT_DELAY=5
CONFIG_SPI_NOR_PAGE_SIZE=256
CONFIG_SPI_NOR_SECTOR_SIZE=4096
CONFIG_FLASH_HAS_PAGE_LAYOUT=y
CONFIG_FLASH_PAGE_LAYOUT=y

3. make, you can find undeclared DT_JEDEC_SPI_NOR_0_ERASE_BLOCK_SIZE & DT_JEDEC_SPI_NOR_0_WRITE_BLOCK_SIZE

Expected behavior
Build Pass & Spi-nor work well

Additional context
If the spi-flash be put in chosen, the DT_JEDEC_SPI_NOR_0_ERASE_BLOCK_SIZE & DT_JEDEC_SPI_NOR_0_WRITE_BLOCK_SIZE will be create

	chosen {
		zephyr,console = &uart0;
		zephyr,shell-uart = &uart0;
		zephyr,sram = &sram0;
		zephyr,flash = &w25x16vsi0;
		//zephyr,flash = &flash0;
	};

but, remove the internal flash0 will cause other build error

[jimparis]

Hi,
I raised this same issue in PR #15225
This patch should help: cc5ffd0

[lgl88911]

@jimparis Thanks, I use your patch, build pass