Revert "ANDROID: mm: cma: export __cma_alloc()"

This reverts commit 5559b861a3.

Upstream dropped __cma_alloc() in commit 9bda131c60 ("mm: cma: add
cma_alloc_frozen{_compound}()"), and replaced it with an alternative
__cma_alloc_frozen() but that doesn't increment the page's refcount.
Pixel should convert to use plain cma_alloc() instead.

Bug: 308881290
Cc: Juan Yescas <jyescas@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Change-Id: I27ea5d46481f46ff290737ef12bece6e01dbb990
Signed-off-by: Carlos Llamas <cmllamas@google.com>

include/linux/cma.h

@@ -47,8 +47,6 @@ extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 					unsigned int order_per_bit,
 					const char *name,
 					struct cma **res_cma);
-extern struct page *__cma_alloc(struct cma *cma, unsigned long count,
-				unsigned int align, gfp_t gfp);
 extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int align,
 			      bool no_warn);
 extern bool cma_pages_valid(struct cma *cma, const struct page *pages, unsigned long count);

mm/cma.c

@@ -883,7 +883,7 @@ out:
 	return ret;
 }
 
-struct page *__cma_alloc(struct cma *cma, unsigned long count,
+static struct page *__cma_alloc(struct cma *cma, unsigned long count,
 		       unsigned int align, gfp_t gfp)
 {
 	struct page *page = NULL;
@@ -944,7 +944,6 @@ struct page *__cma_alloc(struct cma *cma, unsigned long count,
 
 	return page;
 }
-EXPORT_SYMBOL_GPL(__cma_alloc);
 
 /**
  * cma_alloc() - allocate pages from contiguous area