earlycon: Fix __earlycon_table stride

The compiler and the linker must agree on the alignment of
struct earlycon_id; empirical testing and commit 07fca0e5
("tracing: Properly align linker defined symbols") suggests
32-byte alignment is the LCD.

Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>