Revert "swiotlb: panic if nslabs is too small"

This reverts commit 0bf28fc.

Reasons:
  1. new panic()s shouldn't be added [1].
  2. It does no "cleanup" but breaks MIPS [2].

[1]: https://lore.kernel.org/r/CAHk-=wit-DmhMfQErY29JSPjFgebx_Ld+pnerc4J2Ag990WwAA@mail.gmail.com/
[2]: https://lore.kernel.org/r/20220820012031.1285979-1-yuzhao@google.com/

Fixes: 0bf28fc ("swiotlb: panic if nslabs is too small")
Signed-off-by: Yu Zhao <yuzhao@google.com>

kernel/dma/swiotlb.c

@@ -325,10 +325,6 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
 	if (!default_nareas)
 		swiotlb_adjust_nareas(num_possible_cpus());
 
-	nslabs = default_nslabs;
-	if (nslabs < IO_TLB_MIN_SLABS)
-		panic("%s: nslabs = %lu too small\n", __func__, nslabs);
-
 	/*
 	 * By default allocate the bounce buffer memory from low memory, but
 	 * allow to pick a location everywhere for hypervisors with guest
@@ -341,8 +337,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
 	else
 		tlb = memblock_alloc_low(bytes, PAGE_SIZE);
 	if (!tlb) {
-		pr_warn("%s: Failed to allocate %zu bytes tlb structure\n",
-			__func__, bytes);
+		pr_warn("%s: failed to allocate tlb structure\n", __func__);
 		return;
 	}