bus: ti-sysc: Correct misdocumentation of 'sysc_ioremap()'

Fixes the following W=1 kernel build warning(s):

 drivers/bus/ti-sysc.c:867: warning: expecting prototype for syc_ioremap(). Prototype was for sysc_ioremap() instead

Cc: Tony Lindgren <tony@atomide.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: linux-omap@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>