nds32: introduce macros for bit manipulation

nds32: introduce macros for bit manipulation

U-Boot does not compile for the adp-ag101 boards since
commit f6c3b34697bf8bf05cb4e81c2fd3cadb9a98daea (mmc:
update Faraday FTSDC010 for rw performance)

The driver assumes that the bit manipulation macros
are provided by all architectures. This is not the
case for nds32 and it causes a build error like this:

  ftsdc010_mci.c: In function 'ftsdc010_clkset':
  ftsdc010_mci.c:118: warning: implicit declaration of function 'setbits_le32'
  ftsdc010_mci.c:123: warning: implicit declaration of function 'clrbits_le32'
  drivers/mmc/libmmc.o: In function `ftsdc010_request':
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:234: undefined reference to `setbits_le32'
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:243: undefined reference to `clrbits_le32'
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:234: undefined reference to `clrbits_le32'
  drivers/mmc/libmmc.o: In function `ftsdc010_clkset':
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:118: undefined reference to `clrbits_le32'
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:118: undefined reference to `clrbits_le32'
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:121: undefined reference to `setbits_le32'
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:123: undefined reference to `setbits_le32'
  /devel/u-boot.git/drivers/mmc/ftsdc010_mci.c:123: undefined reference to `setbits_le32'

The patch adds bit manipulation macros for the
nds32 architecture to avoid the errors. The macros
are copied from the ARM implementation.

Compile tested only.

Cc: Kuo-Jung Su <dantesu@faraday-tech.com>
Cc: Macpaul Lin <macpaul@andestech.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>