Convert CONFIG_SYS_NAND_PAGE_COUNT to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_NAND_PAGE_COUNT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
index 04bf910..8739f3e 100644
--- a/drivers/mtd/nand/raw/Kconfig
+++ b/drivers/mtd/nand/raw/Kconfig
@@ -370,6 +370,13 @@
 	  board. This is the multiple of NAND_PAGE_SIZE and the number of
 	  pages.
 
+config SYS_NAND_PAGE_COUNT
+	hex "NAND chip page count"
+	depends on SPL_NAND_SUPPORT && (NAND_ATMEL || NAND_MXC || \
+		SPL_NAND_AM33XX_BCH || SPL_NAND_LOAD || SPL_NAND_SIMPLE)
+	help
+	  Number of pages in the NAND chip.
+
 config SYS_NAND_PAGE_SIZE
 	hex "NAND chip page size"
 	depends on ARCH_SUNXI || NAND_OMAP_GPMC || NAND_LPC32XX_SLC || \