cann: update L2_NORM op support

[TecJesh]

Currently, the CANN backend does not support the l2_norm operator. Add support for the l2_norm operator to the CANN backend.

[noemotiovon]

LGTM! Just a tiny issue.

[hipudding]

Test case passed:
Backend 1/3: CANN0
Device description: Ascend910B4
Device memory: 30196 MB (29811 MB free)

new_pool_for_device: device 0 use vmm pool
L2_NORM(type=f32,ne=[64,5,4,3]): OK
L2_NORM(type=f32,ne=[64,5,4,3]): OK
L2_NORM(type=f32,ne=[64,5,4,3]): OK
L2_NORM(type=f32,ne=[64,5,4,3]): OK
L2_NORM(type=f32,ne=[64,5,4,3]): OK
5/5 tests passed
Backend CANN0: OK
Backend 2/3: CANN1
Skipping
Backend 3/3: CPU
Skipping
3/3 backends passed
OK