cli: add ability to read/write memory of different bus width
cli: add ability to read/write memory of different bus width

This adds an optional extra parameter to the 'rw' command. When the
first argument is .b or .s, the access size becomes 8 pr 16 bits
respectively.

BRANCH=none
BUG=none
TEST=on the EC console:
> rw  0x10000
read 0x10000 = 0x00000000
> rw .b 0x10000 0x55
write 0x10000 = 0x55
> rw  0x10000
read 0x10000 = 0x00000055
> rw .b 0x10000
read 0x10000 = 0x55
> rw .s 0x10002
read 0x10002 = 0x0000
> rw .s 0x10002 0x1234
write 0x10002 = 0x1234
> rw 0x10000
read 0x10000 = 0x12340055
>  rw .b 0x10000
read 0x10000 = 0x55
>  rw .b 0x10001
read 0x10001 = 0x00
> rw .b 0x10002
read 0x10002 = 0x34
> rw .b 0x10003
read 0x10003 = 0x12
> rw .s 0x10000
read 0x10000 = 0x0055
> rw .s 0x10002
read 0x10002 = 0x1234
> rw . 0x10002
Parameter 1 invalid
Usage: rw addr [.{b|s}] [value]
>

Change-Id: Iad1a4b3e297253ffdbf13afeede8ade9451eb11a
Signed-off-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/268897
Reviewed-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,fourier49/BIZ_EC,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,fourier49/BZ_DEV_EC,fourier49/BZ_DEV_EC,fourier49/BZ_DEV_EC,md5555/ec,coreboot/chrome-ec,fourier49/BIZ_EC,coreboot/chrome-ec,fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,fourier49/BIZ_EC,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,md5555/ec