ARM: at91: Convert SPL_GENERATE_ATMEL_PMECC_HEADER to Kconfig

This commit converts the following items to Kconfig:

CONFIG_ATMEL_NAND_HWECC
CONFIG_ATMEL_NAND_HW_PMECC
CONFIG_PMECC_CAP
CONFIG_PMECC_SECTOR_SIZE
CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER

[PMECC References]
https://www.at91.com/linux4sam/bin/view/Linux4SAM/PmeccConfigure
https://www.at91.com/linux4sam/bin/view/Linux4SAM/AT91Bootstrap

[Mailing List Thread]
https://lists.denx.de/pipermail/u-boot/2018-December/350666.html

Fixes: 5541543f ("configs: at91: Remove CONFIG_SYS_EXTRA_OPTIONS assignment")
[trini: Make the migration be size neutral and possibly not fix the
above in all cases]
Reported-by: Daniel Evans <photonthunder@gmail.com>
Cc: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Derald D. Woods <woods.technical@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/sama5d4_xplained_spiflash_defconfig b/configs/sama5d4_xplained_spiflash_defconfig
index a89dd11..ef08339 100644
--- a/configs/sama5d4_xplained_spiflash_defconfig
+++ b/configs/sama5d4_xplained_spiflash_defconfig
@@ -58,6 +58,8 @@
 CONFIG_GENERIC_ATMEL_MCI=y
 CONFIG_NAND=y
 CONFIG_NAND_ATMEL=y
+CONFIG_PMECC_CAP=8
+CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER=y
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_ATMEL=y