powerpc/fadump: Mark fadump_calculate_reserve_size as __init

If fadump_calculate_reserve_size() is not inlined, there is a modpost
warning:

WARNING: modpost: vmlinux.o(.text+0x5196c): Section mismatch in
reference from the function fadump_calculate_reserve_size() to the
function .init.text:parse_crashkernel()
The function fadump_calculate_reserve_size() references
the function __init parse_crashkernel().
This is often because fadump_calculate_reserve_size lacks a __init
annotation or the annotation of parse_crashkernel is wrong.

fadump_calculate_reserve_size() calls parse_crashkernel(), which is
marked as __init and fadump_calculate_reserve_size() is called from
within fadump_reserve_mem(), which is also marked as __init.

Mark fadump_calculate_reserve_size() as __init to fix the section
mismatch. Additionally, remove the inline keyword as it is not necessary
to inline this function; the compiler is still free to do so if it feels
it is worthwhile since commit 889b3c1245 ("compiler: remove
CONFIG_OPTIMIZE_INLINING entirely").

Fixes: 11550dc0a0 ("powerpc/fadump: reuse crashkernel parameter for fadump memory reservation")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://github.com/ClangBuiltLinux/linux/issues/1300
Link: https://lore.kernel.org/r/20210302195013.2626335-1-nathan@kernel.org

arch/powerpc/kernel/fadump.c

@@ -292,7 +292,7 @@ static void fadump_show_config(void)
  * that is required for a kernel to boot successfully.
  *
  */
-static inline u64 fadump_calculate_reserve_size(void)
+static __init u64 fadump_calculate_reserve_size(void)
 {
 	u64 base, size, bootmem_min;
 	int ret;