mtd: rawnand: stm32_fmc2: add STM32 FMC2 NAND flash controller driver

The driver adds the support for the STMicroelectronics FMC2 NAND
Controller found on STM32MP SOCs.

This patch adds the polling mode, a basic mode that do not need
any DMA channels.

Only NAND_ECC_HW mode is actually supported.
The driver supports a maximum 8k page size.
The following ECC strength and step size are currently supported:
 - nand-ecc-strength = <8>, nand-ecc-step-size = <512> (BCH8)
 - nand-ecc-strength = <4>, nand-ecc-step-size = <512> (BCH4)
 - nand-ecc-strength = <1>, nand-ecc-step-size = <512> (Extended ECC
   based on Hamming)

This patch has been tested on Micron MT29F8G08ABACAH4.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
index c61e3f3..b10e718 100644
--- a/drivers/mtd/nand/raw/Makefile
+++ b/drivers/mtd/nand/raw/Makefile
@@ -65,6 +65,7 @@
 obj-$(CONFIG_NAND_PLAT) += nand_plat.o
 obj-$(CONFIG_NAND_SUNXI) += sunxi_nand.o
 obj-$(CONFIG_NAND_ZYNQ) += zynq_nand.o
+obj-$(CONFIG_NAND_STM32_FMC2) += stm32_fmc2_nand.o
 
 else  # minimal SPL drivers