ARM: davinci: fix build breakage with DEBUG_LL

commit fcf7157b

 ("ARM: davinci: serial: get rid of davinci_uart_config")
introduced build breakage because of a misplaced
header file include which cause a bunch of errors when
the file is included in assembly code (like debug-macro.S)

Fix the build breakage.

Reported-by: Alexander Holler <holler@ahsoftware.de>
Tested-by: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>