kcalloc() doesn't do much more than calling kzalloc(), and gcc has better optimizing opportunities when it's inlined.
The result of this patch with a fulll kernel compile (roughly equivalent to "make allyesconfig") shows a minimal size improvement:
text data bss dec hex filename
25864955 5891214 2012840 33769009 2034631 vmlinux-before
25864635 5891206 2012840 33768681 20344e9 vmlinux-staticinline
Signed-off-by: Adrian Bunk <bunk@xxxxxxxxx>