sf: Rename spi_flash files

Renamed:
spi_flash.c -> sf.c
spi_flash_internal.h -> sf_internal.h
spi_flash_ops.c -> sf_ops.c
spi_flash_probe.c -> sf_probe.c

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
diff --git a/drivers/mtd/spi/Makefile b/drivers/mtd/spi/Makefile
index 0fa867d..86ffc59 100644
--- a/drivers/mtd/spi/Makefile
+++ b/drivers/mtd/spi/Makefile
@@ -15,9 +15,9 @@
 endif
 
 ifdef CONFIG_CMD_SF
-COBJS-y        += spi_flash.o
+COBJS-y        += sf.o
 endif
-COBJS-$(CONFIG_SPI_FLASH) += spi_flash_probe.o spi_flash_ops.o
+COBJS-$(CONFIG_SPI_FLASH) += sf_probe.o sf_ops.o
 COBJS-$(CONFIG_SPI_FRAM_RAMTRON) += ramtron.o
 COBJS-$(CONFIG_SPI_M95XXX) += eeprom_m95xxx.o