msm: sps: Add integer wrap check for debugfs buffer

When converting debugfs buffer size to kilobytes value
there is a possible integer overflow and it may result
into negative value.

Fix the issue by adding integer wrap check for buffer
size just before conversion.

idea is taken here -
https://github.com/flar2/ElementalX-N5/commit/c519cf1278d7f9dc2b7b02c7d466e309c8bd6968