cmd: dm: allow for selecting uclass and device

cmd: dm: allow for selecting uclass and device

The output from "dm tree" or "dm uclass" is a bit annoying
if the number of devices available on the system is huge.
(This is especially true on sandbox when I debug some DM code.)

With this patch, we can specify the uclass name or the device
name that we are interested in in order to limit the output.

For instance,

=> dm uclass usb
uclass 121: usb
0     usb@1 @ 0bcff8b0, seq 1

uclass 124: usb

=> dm tree usb:usb@1
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 usb           0  [   ]   usb_sandbox           usb@1
 usb_hub       0  [   ]   usb_hub               `-- hub
 usb_emul      0  [   ]   usb_sandbox_hub           `-- hub-emul
 usb_emul      1  [   ]   usb_sandbox_flash             |-- flash-stick@0
 usb_emul      2  [   ]   usb_sandbox_flash             |-- flash-stick@1
 usb_emul      3  [   ]   usb_sandbox_flash             |-- flash-stick@2
 usb_emul      4  [   ]   usb_sandbox_keyb              `-- keyb@3

If you want forward-matching against a uclass or udevice name,
you can specify "-e" option.

=> dm uclass -e usb
uclass 15: usb_emul
0     hub-emul @ 0bcffb00, seq 0
1     flash-stick@0 @ 0bcffc30, seq 1
2     flash-stick@1 @ 0bcffdc0, seq 2
3     flash-stick@2 @ 0bcfff50, seq 3
4     keyb@3 @ 0bd000e0, seq 4

uclass 64: usb_mass_storage

uclass 121: usb
0     usb@1 @ 0bcff8b0, seq 1

uclass 122: usb_dev_generic

uclass 123: usb_hub
0     hub @ 0bcff9b0, seq 0

uclass 124: usb

=> dm tree -e usb
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 usb           0  [   ]   usb_sandbox           usb@1
 usb_hub       0  [   ]   usb_hub               `-- hub
 usb_emul      0  [   ]   usb_sandbox_hub           `-- hub-emul
 usb_emul      1  [   ]   usb_sandbox_flash             |-- flash-stick@0
 usb_emul      2  [   ]   usb_sandbox_flash             |-- flash-stick@1
 usb_emul      3  [   ]   usb_sandbox_flash             |-- flash-stick@2
 usb_emul      4  [   ]   usb_sandbox_keyb              `-- keyb@3

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>