ASoC: loongson: Fix invalid position error in ls_pcm_pointer

ASoC: loongson: Fix invalid position error in ls_pcm_pointer

The "invalid position" error occurred when the DMA position descriptor
returned an invalid address value (e.g., pos = -1048838144). This happened
because the `bytes_to_frames()` function returns a signed value, but when
`addr < runtime->dma_addr`, the subtraction produces a negative result that
gets interpreted as a large unsigned integer in comparisons.
when the addr is abnormal, for example,the DMA controller is abnormal in
hardware,x=0 should not be a point(x == runtime->buffer_size),but a range,
which includes the addr address being less than runtime ->dma1-adr, and
the addr exceeding the DMA address range.the value of pos should not better
a negative，return 0, maybe better.

[   32.834431][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.845019][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.855588][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.866145][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.995394][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   33.006025][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   33.016748][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144

Signed-off-by: Li Jun <lijun01@kylinos.cn>
[Remove XRUN reporting I'd mistakenly avised adding on prior review -- broonie]
Link: https://patch.msgid.link/20260611010045.3668574-1-lijun01@kylinos.cn
Signed-off-by: Mark Brown <broonie@kernel.org>