accel/amdxdna: Use unsigned long for nr_pages in amdxdna_hmm_register()

accel/amdxdna: Use unsigned long for nr_pages in amdxdna_hmm_register()

nr_pages is declared as u32 in amdxdna_hmm_register(), which may not be
large enough to represent the number of pages for large mappings.

Use unsigned long for nr_pages to avoid potential overflow.

Fixes: ac49797c1815 ("accel/amdxdna: Add GEM buffer object management")
Reviewed-by: Max Zhen <max.zhen@amd.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260616061532.3533469-1-lizhi.hou@amd.com