bootm: Export bootm_decomp_image()

Export this function for testing. Also add a parameter so that values other
than CONFIG_SYS_BOOTM_LEN can be used for the maximum uncompressed size.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/bootm.h b/include/bootm.h
index b3d1a62..6181488 100644
--- a/include/bootm.h
+++ b/include/bootm.h
@@ -56,4 +56,21 @@
 
 void arch_preboot_os(void);
 
+/**
+ * bootm_decomp_image() - decompress the operating system
+ *
+ * @comp:	Compression algorithm that is used (IH_COMP_...)
+ * @load:	Destination load address in U-Boot memory
+ * @image_start Image start address (where we are decompressing from)
+ * @type:	OS type (IH_OS_...)
+ * @load_bug:	Place to decompress to
+ * @image_buf:	Address to decompress from
+ * @image_len:	Number of bytes in @image_buf to decompress
+ * @unc_len:	Available space for decompression
+ * @return 0 if OK, -ve on error (BOOTM_ERR_...)
+ */
+int bootm_decomp_image(int comp, ulong load, ulong image_start, int type,
+		       void *load_buf, void *image_buf, ulong image_len,
+		       uint unc_len, ulong *load_end);
+
 #endif