net: tsec: Cleanup tsec regs init and fix __iomem warns

Remove tsec_t typedef.  Define macros as getters of
tsec and mdio register memory regions, for consistent
initialization of various 'regs' fields and also to
manage overly long initialization lines.
Use the __iomem address space marker to address sparse
warnings in tsec.c where IO accessors are used, like:

tsec.c:394:19: warning: incorrect type in argument 1 (different
address spaces)
tsec.c:394:19:    expected unsigned int volatile [noderef]
<asn:2>*addr
tsec.c:394:19:    got unsigned int *<noident>
[...]

Add the __iomem address space marker for the tsec pointers
to struct tsec_mii_mng memory mapped register regions.
This solves the sparse warnings for mixig normal pointers
with __iomem pointers for tsec.

Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>