modinfo: fix module parsing with kernel >= 2.6.37

modinfo: fix module parsing with kernel >= 2.6.37

display() function returns the length of the value we are displaying + 1.
As a consequence, if we have field=value\0field=value\0field=value in the
binary, then the second occurence will be skipped as ptr will miss the first
character of the following field.

Example trying to list aliases from ixgbe.ko on a 3.2 kernel.

- In the module we have:
alias=pci:v00008086d00001560sv*sd*bc*sc*i*\0
alias=pci:v00008086d0000154Asv*sd*bc*sc*i*\0
alias=pci:v00008086d00001557sv*sd*bc*sc*i*\0
alias=pci:v00008086d0000154Fsv*sd*bc*sc*i*\0
alias=pci:v00008086d0000154Dsv*sd*bc*sc*i*\0
...

- Using modinfo -F alias ixgbe returns:
alias:          pci:v00008086d00001560sv*sd*bc*sc*i*
alias:          pci:v00008086d00001557sv*sd*bc*sc*i*
alias:          pci:v00008086d0000154Dsv*sd*bc*sc*i*
...

This problem appeared with kernel commit "modules: no need to align .modinfo
strings" b6472776816af1ed52848c93d26e3edb3b17adab in 2.6.37.

Fix this by not trusting display() return value but increment ptr by strlen(ptr)
(the same way as depmod.c does).

Signed-off-by: David Marchand <david.marchand@6wind.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>