perf: Remove redundant condition for AUX buffer size

perf: Remove redundant condition for AUX buffer size

It is already checked whether the VMA size is the same as
nr_pages * PAGE_SIZE, so later checking both:

      aux_size == vma_size && aux_size == nr_pages * PAGE_SIZE

is redundant. Remove the vma_size check as nr_pages is what is actually
used in the allocation function. That prepares for splitting out the buffer
allocation into separate functions, so that only nr_pages needs to be
handed in.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250812104018.424519320@infradead.org