drm/etnaviv: dump: fix sparse warnings

This patch fixes the following sparse warnings, by adding the missing endianess
conversion functions.

| etnaviv/etnaviv_dump.c:78:26: warning: restricted __le32 degrades to integer
| etnaviv/etnaviv_dump.c:88:26: warning: incorrect type in assignment (different base types)
| etnaviv/etnaviv_dump.c:88:26:    expected restricted __le32 [usertype] reg
| etnaviv/etnaviv_dump.c:88:26:    got unsigned short const
| etnaviv/etnaviv_dump.c:89:28: warning: incorrect type in assignment (different base types)
| etnaviv/etnaviv_dump.c:89:28:    expected restricted __le32 [usertype] value
| etnaviv/etnaviv_dump.c:89:28:    got unsigned int
| etnaviv/etnaviv_dump.c:210:43: warning: incorrect type in assignment (different base types)
| etnaviv/etnaviv_dump.c:210:43:    expected restricted __le32
| etnaviv/etnaviv_dump.c:210:43:    got long

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>